os/doc
3
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
doc/en_US.ISO8859-1/books/handbook/disks/chapter.sgml
Jim Mock 91c5268d54 Add a section on floppy drives to the disks chapter. 
PR:			33164, 34474
33164 Submitted by:	Julio Merino <juli@merino.net>
34474 Submitted by:	Tom Rhodes <darklogik@pittgoth.com>
2002-01-31 07:57:52 +00:00

2256 lines
91 KiB
Text
Raw Blame History

<!--
The FreeBSD Documentation Project
$FreeBSD$
-->
<chapter id="disks">
<title>Storage</title>
<sect1 id="disks-synopsis">
<title>Synopsis</title>
<para>This chapter covers the use of disks in FreeBSD. This
includes memory-backed disks, network-attached disks, and
standard SCSI/IDE storage devices.</para>
<para>After reading this chapter, you will know:</para>
<itemizedlist>
<listitem><para>The terminology FreeBSD uses to describe the
organization of data on a physical disk (partitions and slices).</para>
</listitem>
<listitem><para>How to mount and unmount filesystems.</para>
</listitem>
<listitem><para>How to add additional hard disks to your system.</para>
</listitem>
<listitem><para>How to setup virtual filesystems, such as memory
disks.</para></listitem>
<listitem>
<para>How to use quotas to limit disk space usage.</para>
</listitem>
<listitem>
<para>How to create and burn CDs and DVDs on FreeBSD.</para>
</listitem>
<listitem>
<para>The various storage media options for backups.</para>
</listitem>
<listitem>
<para>How to use backup programs available under FreeBSD.</para>
</listitem>
<listitem>
<para>How to backup to floppy disks.</para>
</listitem>
</itemizedlist>
</sect1>
<sect1 id="disks-naming">
<title>Device Names</title>
<para>The following is a list of physical storage devices
supported in FreeBSD, and the device names associated with
them.</para>
<table id="disk-naming-physical-table">
<title>Physical Disk Naming Conventions</title>
<tgroup cols="2">
<thead>
<row>
<entry>Drive type</entry>
<entry>Drive device name</entry>
</row>
</thead>
<tbody>
<row>
<entry>IDE hard drives</entry>
<entry><literal>ad</literal>
</row>
<row>
<entry>IDE CDROM drives</entry>
<entry><literal>acd</literal>
</row>
<row>
<entry>SCSI hard drives and USB Mass storage devices</entry>
<entry><literal>da</literal>
</row>
<row>
<entry>SCSI CDROM drives</entry>
<entry><literal>cd</literal></entry>
</row>
<row>
<entry>Assorted non-standard CDROM drives</entry>
<entry><literal>mcd</literal> for Mitsumi CD-ROM,
<literal>scd</literal> for Sony CD-ROM,
<literal>matcd</literal> for Matsushita/Panasonic CD-ROM
</entry>
</row>
<row>
<entry>Floppy drives</entry>
<entry><literal>fd</literal></entry>
</row>
<row>
<entry>SCSI tape drives</entry>
<entry><literal>sa</literal>
</row>
<row>
<entry>IDE tape drives</entry>
<entry><literal>ast</literal>
</row>
<row>
<entry>Flash drives</entry>
<entry><literal>fla</literal> for DiskOnChip Flash device
</row>
<row>
<entry>RAID drives</entry>
<entry><literal>myxd</literal> for Mylex, and
<literal>amrd</literal> for AMI MegaRAID,
<literal>idad</literal> for Compaq Smart RAID.
</row>
</tbody>
</tgroup>
</table>
</sect1>
<sect1 id="disks-adding">
<sect1info>
<authorgroup>
<author>
<firstname>David</firstname>
<surname>O'Brien</surname>
<contrib>Originally contributed by </contrib>
</author>
</authorgroup>
<!-- 26 Apr 1998 -->
</sect1info>
<title>Adding Disks</title>
<indexterm>
<primary>disks</primary>
<secondary>adding</secondary>
</indexterm>
<para>Lets say we want to add a new SCSI disk to a machine that
currently only has a single drive. First turn off the computer
and install the drive in the computer following the instructions
of the computer, controller, and drive manufacturer. Due to the
wide variations of procedures to do this, the details are beyond
the scope of this document.</para>
<para>Login as user <username>root</username>. After you have installed the
drive, inspect <filename>/var/run/dmesg.boot</filename> to ensure the new
disk was found. Continuing with our example, the newly added drive will
be <devicename>da1</devicename> and we want to mount it on
<filename>/1</filename> (if you are adding an IDE drive, the device name
will be <devicename>wd1</devicename> in pre-4.0 systems, or
<devicename>ad1</devicename> in most 4.X systems).</para>
<indexterm><primary>partitions</primary></indexterm>
<indexterm><primary>slices</primary></indexterm>
<indexterm>
<primary><command>fdisk</command></primary>
</indexterm>
<para>Because FreeBSD runs on IBM-PC compatible computers, it must
take into account the PC BIOS partitions. These are different
from the traditional BSD partitions. A PC disk has up to four
BIOS partition entries. If the disk is going to be truly
dedicated to FreeBSD, you can use the
<emphasis>dedicated</emphasis> mode. Otherwise, FreeBSD will
have to live within one of the PC BIOS partitions. FreeBSD
calls the PC BIOS partitions <emphasis>slices</emphasis> so as
not to confuse them with traditional BSD partitions. You may
also use slices on a disk that is dedicated to FreeBSD, but used
in a computer that also has another operating system installed.
This is to not confuse the <command>fdisk</command> utility of
the other operating system.</para>
<para>In the slice case the drive will be added as
<filename>/dev/da1s1e</filename>. This is read as: SCSI disk,
unit number 1 (second SCSI disk), slice 1 (PC BIOS partition 1),
and <filename>e</filename> BSD partition. In the dedicated
case, the drive will be added simply as
<filename>/dev/da1e</filename>.</para>
<sect2>
<title>Using &man.sysinstall.8;</title>
<indexterm>
<primary><application>sysinstall</application></primary>
<secondary>adding disks</secondary>
</indexterm>
<indexterm>
<primary>su</primary>
</indexterm>
<procedure>
<step>
<title>Navigating <application>Sysinstall</application></title>
<para>You may use <command>/stand/sysinstall</command> to
partition and label a new disk using its easy to use menus.
Either login as user <username>root</username> or use the
<command>su</command> command. Run
<command>/stand/sysinstall</command> and enter the
<literal>Configure</literal> menu. Within the
<literal>FreeBSD Configuration Menu</literal>, scroll down and
select the <literal>Partition</literal> item. Next you should
be presented with a list of hard drives installed in your
system. If you do not see <literal>da1</literal> listed, you
need to recheck your physical installation and
<command>dmesg</command> output in the file
<filename>/var/run/dmesg.boot</filename>.</para>
</step>
<step>
<title>FDISK Partition Editor</title>
<para>Select <literal>da1</literal> to enter the <literal>FDISK
Partition Editor</literal>. Type <userinput>A</userinput> to
use the entire disk for FreeBSD. When asked if you want to
<quote>remain cooperative with any future possible operating
systems</quote>, answer <literal>YES</literal>. Write the
changes to the disk using <userinput>W</userinput>. Now exit the
FDISK editor by typing <userinput>q</userinput>. Next you will be
asked about the Master Boot Record. Since you are adding a
disk to an already running system, choose
<literal>None</literal>.</para>
</step>
<step>
<title>Disk Label Editor</title>
<indexterm><primary>BSD partitions</primary></indexterm>
<para>Next, <application>Sysinstall</application> will
enter the <literal>Disk Label Editor</literal>. This
is where you will create the traditional BSD partitions. A
disk can have up to eight partitions, labeled
<literal>a-h</literal>.
A few of
the partition labels have special uses. The
<literal>a</literal> partition is used for the root partition
(<filename>/</filename>). Thus only your system disk (e.g,
the disk you boot from) should have an <literal>a</literal>
partition. The <literal>b</literal> partition is used for
swap partitions, and you may have many disks with swap
partitions. The <literal>c</literal> partition addresses the
entire disk in dedicated mode, or the entire FreeBSD slice in
slice mode. The other partitions are for general use.</para>
<para><application>Sysinstall</application>'s Label editor
favors the <literal>e</literal>
partition for non-root, non-swap partitions. Within the
Label editor, create a single file system by typing
<userinput>C</userinput>. When prompted if this will be a FS
(file system) or swap, choose <literal>FS</literal> and type in a
mount point (e.g, <filename>/mnt</filename>). When adding a
disk in post-install mode, <application>Sysinstall</application>
will not create entries
in <filename>/etc/fstab</filename> for you, so the mount point
you specify is not important.</para>
<para>You are now ready to write the new label to the disk and
create a file system on it. Do this by typing
<userinput>W</userinput>. Ignore any errors from
<application>Sysinstall</application> that
it could not mount the new partition. Exit the Label Editor
and <application>Sysinstall</application> completely.</para>
</step>
<step>
<title>Finish</title>
<para>The last step is to edit <filename>/etc/fstab</filename>
to add an entry for your new disk.</para>
</step>
</procedure>
</sect2>
<sect2>
<title>Using Command Line Utilities</title>
<sect3>
<title>Using Slices</title>
<para>This setup will allow your disk to work correctly with
other operating systems that might be installed on your
computer and will not confuse other operating systems'
<command>fdisk</command> utilities. It is recommended
to use this method for new disk installs. Only use
<literal>dedicated</literal> mode if you have a good reason
to do so!</para>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/rda1 bs=1k count=1</userinput>
&prompt.root; <userinput>fdisk -BI da1</userinput> #Initialize your new disk
&prompt.root; <userinput>disklabel -B -w -r da1s1 auto</userinput> #Label it.
&prompt.root; <userinput>disklabel -e da1s1</userinput> # Edit the disklabel just created and add any partitions.
&prompt.root; <userinput>mkdir -p /1</userinput>
&prompt.root; <userinput>newfs /dev/da1s1e</userinput> # Repeat this for every partition you created.
&prompt.root; <userinput>mount -t ufs /dev/da1s1e /1</userinput> # Mount the partition(s)
&prompt.root; <userinput>vi /etc/fstab</userinput> # Add the appropriate entry/entries to your <filename>/etc/fstab</filename>.</screen>
<para>If you have an IDE disk, substitute <filename>ad</filename>
for <filename>da</filename>. On pre-4.X systems use
<filename>wd</filename>.</para>
</sect3>
<sect3>
<title>Dedicated</title>
<indexterm><primary>OS/2</primary></indexterm>
<para>If you will not be sharing the new drive with another operating
system, you may use the <literal>dedicated</literal> mode. Remember
this mode can confuse Microsoft operating systems; however, no damage
will be done by them. IBM's OS/2 however, will
<quote>appropriate</quote> any partition it finds which it does not
understand.</para>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/rda1 bs=1k count=1</userinput>
&prompt.root; <userinput>disklabel -Brw da1 auto</userinput>
&prompt.root; <userinput>disklabel -e da1</userinput> # create the `e' partition
&prompt.root; <userinput>newfs -d0 /dev/rda1e</userinput>
&prompt.root; <userinput>mkdir -p /1</userinput>
&prompt.root; <userinput>vi /etc/fstab</userinput> # add an entry for /dev/da1e
&prompt.root; <userinput>mount /1</userinput></screen>
<para>An alternate method is:</para>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/rda1 count=2</userinput>
&prompt.root; <userinput>disklabel /dev/rda1 | disklabel -BrR da1 /dev/stdin</userinput>
&prompt.root; <userinput>newfs /dev/rda1e</userinput>
&prompt.root; <userinput>mkdir -p /1</userinput>
&prompt.root; <userinput>vi /etc/fstab</userinput> # add an entry for /dev/da1e
&prompt.root; <userinput>mount /1</userinput></screen>
</sect3>
</sect2>
</sect1>
<sect1 id="disks-virtual">
<title>Network, Memory, and File-Based Filesystems</title>
<indexterm><primary>virtual disks</primary></indexterm>
<indexterm>
<primary>disks</primary>
<secondary>virtual</secondary>
</indexterm>
<para>Aside from the disks you physically insert into your computer:
floppies, CDs, hard drives, and so forth; other forms of disks
are understood by FreeBSD - the <firstterm>virtual
disks</firstterm>.</para>
<indexterm><primary>NFS</primary></indexterm>
<indexterm><primary>Coda</primary></indexterm>
<indexterm>
<primary>disks</primary>
<secondary>memory</secondary>
</indexterm>
<para>These include network filesystems such as the <link
linkend="nfs">Network Filesystem</link> and Coda, memory-based
filesystems such as <link linkend="disks-md">md</link> and
file-backed filesystems created by <link
linkend="disks-vnconfig">vnconfig</link> or
<command>mdconfig</command>.</para>
<sect2 id="disks-vnconfig">
<title>vnconfig: File-Backed Filesystem</title>
<indexterm>
<primary>disks</primary>
<secondary>file-backed</secondary>
</indexterm>
<para>&man.vnconfig.8; configures and enables vnode pseudo-disk
devices. A <firstterm>vnode</firstterm> is a representation
of a file, and is the focus of file activity. This means that
&man.vnconfig.8; uses files to create and operate a
filesystem. One possible use is the mounting of floppy or CD
images kept in files.</para>
<para>To mount an existing filesystem image:</para>
<example>
<title>Using vnconfig to mount an Existing Filesystem
Image</title>
<screen>&prompt.root; <userinput>vnconfig vn<replaceable>0</replaceable> <replaceable>diskimage</replaceable></userinput>
&prompt.root; <userinput>mount /dev/vn<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput></screen>
</example>
<para>To create a new filesystem image with vnconfig:</para>
<example>
<title>Creating a New File-Backed Disk with vnconfig</title>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=<replaceable>newimage</replaceable> bs=1k count=<replaceable>5</replaceable>k</userinput>
5120+0 records in
5120+0 records out
&prompt.root; <userinput>vnconfig -s labels -c vn<replaceable>0</replaceable> <replaceable>newimage</replaceable></userinput>
&prompt.root; <userinput>disklabel -r -w vn<replaceable>0</replaceable> auto</userinput>
&prompt.root; <userinput>newfs vn<replaceable>0</replaceable>c</userinput>
Warning: 2048 sector(s) in last cylinder unallocated
/dev/rvn0c: 10240 sectors in 3 cylinders of 1 tracks, 4096 sectors
5.0MB in 1 cyl groups (16 c/g, 32.00MB/g, 1280 i/g)
super-block backups (for fsck -b #) at:
32
&prompt.root; <userinput>mount /dev/vn<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>df <replaceable>/mnt</replaceable></userinput>
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/vn0c 4927 1 4532 0% /mnt</screen>
</example>
</sect2>
<sect2 id="disks-md">
<title>md: Memory Filesystem</title>
<indexterm>
<primary>disks</primary>
<secondary>memory filesystem</secondary>
</indexterm>
<para><devicename>md</devicename> is a simple, efficient means to create memory
filesystems.</para>
<para>Simply take a filesystem you have prepared with, for
example, &man.vnconfig.8;, and:</para>
<example>
<title>md Memory Disk</title>
<screen>&prompt.root; <userinput>dd if=<replaceable>newimage</replaceable> of=/dev/md<replaceable>0</replaceable></userinput>
5120+0 records in
5120+0 records out
&prompt.root; <userinput>mount /dev/md<replaceable>0c</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>df <replaceable>/mnt</replaceable></userinput>
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0c 4927 1 4532 0% /mnt</screen>
</example>
</sect2>
</sect1>
<sect1 id="quotas">
<title>File System Quotas</title>
<indexterm>
<primary>accounting</primary>
<secondary>disk space</secondary>
</indexterm>
<indexterm><primary>disk quotas</primary></indexterm>
<para>Quotas are an optional feature of the operating system that
allow you to limit the amount of disk space and/or the number of
files a user or members of a group may allocate on a per-file
system basis. This is used most often on timesharing systems where
it is desirable to limit the amount of resources any one user or
group of users may allocate. This will prevent one user or group
of users from consuming all of the available disk space.</para>
<sect2>
<title>Configuring Your System to Enable Disk Quotas</title>
<para>Before attempting to use disk quotas, it is necessary to make
sure that quotas are configured in your kernel. This is done by
adding the following line to your kernel configuration
file:</para>
<programlisting>options QUOTA</programlisting>
<para>The stock <filename>GENERIC</filename> kernel does not have
this enabled by default, so you will have to configure, build and
install a custom kernel in order to use disk quotas. Please refer
to <xref linkend="kernelconfig"> for more information on kernel
configuration.</para>
<para>Next you will need to enable disk quotas in
<filename>/etc/rc.conf</filename>. This is done by adding the
line:</para>
<programlisting>enable_quotas=<quote>YES</quote></programlisting>
<indexterm>
<primary>disk quotas</primary>
<secondary>checking</secondary>
</indexterm>
<para>For finer control over your quota startup, there is an
additional configuration variable available. Normally on bootup,
the quota integrity of each file system is checked by the
<command>quotacheck</command> program. The
<command>quotacheck</command> facility insures that the data in
the quota database properly reflects the data on the file system.
This is a very time consuming process that will significantly
affect the time your system takes to boot. If you would like to
skip this step, a variable in <filename>/etc/rc.conf</filename>
is made available for the purpose:</para>
<programlisting>check_quotas=<quote>NO</quote></programlisting>
<para>If you are running FreeBSD prior to 3.2-RELEASE, the
configuration is simpler, and consists of only one variable. Set
the following in your <filename>/etc/rc.conf</filename>:</para>
<programlisting>check_quotas=<quote>YES</quote></programlisting>
<para>Finally you will need to edit <filename>/etc/fstab</filename>
to enable disk quotas on a per-file system basis. This is where
you can either enable user or group quotas or both for all of your
file systems.</para>
<para>To enable per-user quotas on a file system, add the
<literal>userquota</literal> option to the options field in the
<filename>/etc/fstab</filename> entry for the file system you want
to enable quotas on. For example:</para>
<programlisting>/dev/da1s2g /home ufs rw,userquota 1 2</programlisting>
<para>Similarly, to enable group quotas, use the
<literal>groupquota</literal> option instead of
<literal>userquota</literal>. To enable both user and
group quotas, change the entry as follows:</para>
<programlisting>/dev/da1s2g /home ufs rw,userquota,groupquota 1 2</programlisting>
<para>By default, the quota files are stored in the root directory of
the file system with the names <filename>quota.user</filename> and
<filename>quota.group</filename> for user and group quotas
respectively. See &man.fstab.5; for more
information. Even though the &man.fstab.5; manual page says that
you can specify
an alternate location for the quota files, this is not recommended
because the various quota utilities do not seem to handle this
properly.</para>
<para>At this point you should reboot your system with your new
kernel. <filename>/etc/rc</filename> will automatically run the
appropriate commands to create the initial quota files for all of
the quotas you enabled in <filename>/etc/fstab</filename>, so
there is no need to manually create any zero length quota
files.</para>
<para>In the normal course of operations you should not be required
to run the <command>quotacheck</command>,
<command>quotaon</command>, or <command>quotaoff</command>
commands manually. However, you may want to read their manual pages
just to be familiar with their operation.</para>
</sect2>
<sect2>
<title>Setting Quota Limits</title>
<indexterm>
<primary>disk quotas</primary>
<secondary>limits</secondary>
</indexterm>
<para>Once you have configured your system to enable quotas, verify
that they really are enabled. An easy way to do this is to
run:</para>
<screen>&prompt.root; <userinput>quota -v</userinput></screen>
<para>You should see a one line summary of disk usage and current
quota limits for each file system that quotas are enabled
on.</para>
<para>You are now ready to start assigning quota limits with the
<command>edquota</command> command.</para>
<para>You have several options on how to enforce limits on the
amount of disk space a user or group may allocate, and how many
files they may create. You may limit allocations based on disk
space (block quotas) or number of files (inode quotas) or a
combination of both. Each of these limits are further broken down
into two categories: hard and soft limits.</para>
<indexterm><primary>hard limit</primary></indexterm>
<para>A hard limit may not be exceeded. Once a user reaches his
hard limit he may not make any further allocations on the file
system in question. For example, if the user has a hard limit of
500 blocks on a file system and is currently using 490 blocks, the
user can only allocate an additional 10 blocks. Attempting to
allocate an additional 11 blocks will fail.</para>
<indexterm><primary>soft limit</primary></indexterm>
<para>Soft limits, on the other hand, can be exceeded for a limited
amount of time. This period of time is known as the grace period,
which is one week by default. If a user stays over his or her
soft limit longer than the grace period, the soft limit will
turn into a hard limit and no further allocations will be allowed.
When the user drops back below the soft limit, the grace period
will be reset.</para>
<para>The following is an example of what you might see when you run
the <command>edquota</command> command. When the
<command>edquota</command> command is invoked, you are placed into
the editor specified by the <envar>EDITOR</envar> environment
variable, or in the <command>vi</command> editor if the
<envar>EDITOR</envar> variable is not set, to allow you to edit
the quota limits.</para>
<screen>&prompt.root; <userinput>edquota -u test</userinput></screen>
<programlisting>Quotas for user test:
/usr: blocks in use: 65, limits (soft = 50, hard = 75)
inodes in use: 7, limits (soft = 50, hard = 60)
/usr/var: blocks in use: 0, limits (soft = 50, hard = 75)
inodes in use: 0, limits (soft = 50, hard = 60)</programlisting>
<para>You will normally see two lines for each file system that has
quotas enabled. One line for the block limits, and one line for
inode limits. Simply change the value you want updated to modify
the quota limit. For example, to raise this user's block limit
from a soft limit of 50 and a hard limit of 75 to a soft limit of
500 and a hard limit of 600, change:</para>
<programlisting>/usr: blocks in use: 65, limits (soft = 50, hard = 75)</programlisting>
<para>to:</para>
<programlisting> /usr: blocks in use: 65, limits (soft = 500, hard = 600)</programlisting>
<para>The new quota limits will be in place when you exit the
editor.</para>
<para>Sometimes it is desirable to set quota limits on a range of
uids. This can be done by use of the <option>-p</option> option
on the <command>edquota</command> command. First, assign the
desired quota limit to a user, and then run
<command>edquota -p protouser startuid-enduid</command>. For
example, if user <username>test</username> has the desired quota
limits, the following command can be used to duplicate those quota
limits for uids 10,000 through 19,999:</para>
<screen>&prompt.root; <userinput>edquota -p test 10000-19999</userinput></screen>
<para>For more information see &man.edquota.8;.</para>
</sect2>
<sect2>
<title>Checking Quota Limits and Disk Usage</title>
<indexterm>
<primary>disk quotas</primary>
<secondary>checking</secondary>
</indexterm>
<para>You can use either the <command>quota</command> or the
<command>repquota</command> commands to check quota limits and
disk usage. The <command>quota</command> command can be used to
check individual user or group quotas and disk usage. A user
may only examine his own quota, and the quota of a group he
is a member of. Only the super-user may view all user and group
quotas. The
<command>repquota</command> command can be used to get a summary
of all quotas and disk usage for file systems with quotas
enabled.</para>
<para>The following is some sample output from the
<command>quota -v</command> command for a user that has quota
limits on two file systems.</para>
<programlisting>Disk quotas for user test (uid 1002):
Filesystem blocks quota limit grace files quota limit grace
/usr 65* 50 75 5days 7 50 60
/usr/var 0 50 75 0 50 60</programlisting>
<indexterm><primary>grace period</primary></indexterm>
<para>On the <filename>/usr</filename> file system in the above
example, this user is currently 15 blocks over the soft limit of
50 blocks and has 5 days of the grace period left. Note the
asterisk <literal>*</literal> which indicates that the user is
currently over his quota limit.</para>
<para>Normally file systems that the user is not using any disk
space on will not show up in the output from the
<command>quota</command> command, even if he has a quota limit
assigned for that file system. The <option>-v</option> option
will display those file systems, such as the
<filename>/usr/var</filename> file system in the above
example.</para>
</sect2>
<sect2>
<title>Quotas over NFS</title>
<indexterm><primary>NFS</primary></indexterm>
<para>Quotas are enforced by the quota subsystem on the NFS server.
The &man.rpc.rquotad.8; daemon makes quota information available
to the &man.quota.1; command on NFS clients, allowing users on
those machines to see their quota statistics.</para>
<para>Enable <command>rpc.rquotad</command> in
<filename>/etc/inetd.conf</filename> like so:</para>
<programlisting>rquotad/1 dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad</programlisting>
<para>Now restart <command>inetd</command>:</para>
<screen>&prompt.root; <userinput>kill -HUP `cat /var/run/inetd.pid`</userinput></screen>
</sect2>
</sect1>
<sect1 id="creating-cds">
<sect1info>
<authorgroup>
<author>
<firstname>Mike</firstname>
<surname>Meyer</surname>
<contrib>Contributed by </contrib>
<!-- mwm@mired.org -->
</author>
</authorgroup>
<!-- Apr 2001 -->
</sect1info>
<title>Creating and Using Optical Media (CDs &amp; DVDs)</title>
<indexterm>
<primary>CDROMs</primary>
<secondary>creating</secondary>
</indexterm>
<sect2>
<title>Introduction</title>
<para>CDs have a number of features that differentiate them from
conventional disks. Initially, they were not writable by the
user. They are designed so that they can be read continuously without
delays to move the head between tracks. They are also much easier
to transport between systems than similarly sized media were at the
time.</para>
<para>CDs do have tracks, but this refers to a section of data to
be read continuously and not a physical property of the disk. To
produce a CD on FreeBSD, you prepare the data files that are going
to make up the tracks on the CD, then write the tracks to the
CD.</para>
<indexterm><primary>ISO 9660</primary></indexterm>
<indexterm>
<primary>filesystems</primary>
<secondary>ISO-9660</secondary>
</indexterm>
<para>The ISO 9660 file system was designed to deal with these
differences. It unfortunately codifies file system limits that were
common then. Fortunately, it provides an extension mechanism that
allows properly written CDs to exceed those limits while still
working with systems that do not support those extensions.</para>
<indexterm>
<primary><command>mkisofs</command></primary>
</indexterm>
<para>The <command><link linkend="mkisofs">mkisofs</link></command>
program is used to produce a data file containing an ISO 9660 file
system. It has options that support various extensions, and is
described below. You can install it with the
<port>sysutils/mkisofs</port> port.</para>
<indexterm>
<primary>CD burner</primary>
<secondary>ATAPI</secondary>
</indexterm>
<para>Which tool to use to burn the CD depends on whether your CD burner
is ATAPI or something else. ATAPI CD burners use the <command><link
linkend="burncd">burncd</link></command> program that is part of
the base system. SCSI and USB CD burners should use
<command><link linkend="cdrecord">cdrecord</link></command> from
the <port>sysutils/cdrtools</port> port.</para>
<para><command>burncd</command> has a limited number of
supported drives. To find out if a drive is supported, see
<ulink url="http://freebsd.dk/ata/">CD-R/RW supported
drives</ulink>.</para>
</sect2>
<sect2 id="mkisofs">
<title>mkisofs</title>
<para><command>mkisofs</command> produces an ISO 9660 file system
that is an image of a directory tree in the Unix file system name
space. The simplest usage is:</para>
<screen>&prompt.root; <userinput>mkisofs <option>-o</option> <replaceable>imagefile.iso</replaceable> <replaceable>/path/to/tree</replaceable></userinput></screen>
<indexterm>
<primary>filesystems</primary>
<secondary>ISO-9660</secondary>
</indexterm>
<para>This command will create an <replaceable>imagefile</replaceable>
containing an ISO 9660 file system that is a copy of the tree at
<replaceable>/path/to/tree</replaceable>. In the process, it will
map the file names to names that fit the limitations of the
standard ISO 9660 file system, and will exclude files that have
names uncharacteristic of ISO file systems.</para>
<indexterm>
<primary>filesystems</primary>
<secondary>HFS</secondary>
</indexterm>
<indexterm>
<primary>filesystems</primary>
<secondary>Joliet</secondary>
</indexterm>
<para>A number of options are available to overcome those
restrictions. In particular, <option>-R</option> enables the
Rock Ridge extensions common to Unix systems, <option>-J</option>
enables Joliet extensions used by Microsoft systems, and
<option>-hfs</option> can be used to create HFS file systems used
by MacOS.</para>
<para>For CDs that are going to be used only on FreeBSD systems,
<option>-U</option> can be used to disable all filename
restrictions. When used with <option>-R</option>, it produces a
file system image that is identical to the FreeBSD tree you started
from, though it may violate the ISO 9660 standard in a number of
ways.</para>
<indexterm>
<primary>CDROMs</primary>
<secondary>creating bootable</secondary>
</indexterm>
<para>The last option of general use is <option>-b</option>. This is
used to specify the location of the boot image for use in producing an
<quote>El Torito</quote> bootable CD. This option takes an
argument which is the path to a boot image from the top of the
tree being written to the CD. So, given that
<filename>/tmp/myboot</filename> holds a bootable FreeBSD system
with the boot image in
<filename>/tmp/myboot/boot/cdboot</filename>, you could produce the
image of an ISO 9660 file system in
<filename>/tmp/bootable.iso</filename> like so:</para>
<screen>&prompt.root; <userinput>mkisofs <option>-U</option> <option>-R</option> <option>-b</option> <filename>boot/cdboot</filename> <option>-o</option> <filename>/tmp/bootable.iso</filename> <filename>/tmp/myboot</filename></userinput></screen>
<para>Having done that, if you have <devicename>vn</devicename>
configured in your kernel, you can mount the file system with:</para>
<screen>&prompt.root; <userinput>vnconfig <option>-e</option> <filename>vn0c</filename> <filename>/tmp/bootable.iso</filename></userinput>
&prompt.root; <userinput>mount <option>-t</option> cd9660 <filename>/dev/vn0c</filename> <filename>/mnt</filename></userinput></screen>
<para>At which point you can verify that <filename>/mnt</filename>
and <filename>/tmp/myboot</filename> are identical.</para>
<para>There are many other options you can use with
<command>mkisofs</command> to fine-tune its behavior. In particular:
modifications to an ISO 9660 layout and the creation of Joilet
and HFS discs. See the &man.mkisofs.8; manual page for details.</para>
</sect2>
<sect2 id="burncd">
<title>burncd</title>
<indexterm>
<primary>CDROMs</primary>
<secondary>burning</secondary>
</indexterm>
<para>If you have an ATAPI CD burner, you can use the
<command>burncd</command> command to burn an ISO image onto a
CD. <command>burncd</command> is part of the base system, installed
as <filename>/usr/sbin/burncd</filename>. Usage is very simple, as
it has few options:</para>
<screen>&prompt.root; <userinput>burncd <option>-f</option> <replaceable>cddevice</replaceable> data <replaceable>imagefile.iso</replaceable> fixate</userinput></screen>
<para>Will burn a copy of <replaceable>imagefile.iso</replaceable> on
<replaceable>cddevice</replaceable>. The default device is
<filename>/dev/acd0c</filename>. See &man.burncd.8; for options to
set the write speed, eject the CD after burning, and write audio
data.</para>
</sect2>
<sect2 id="cdrecord">
<title>cdrecord</title>
<para>If you do not have an ATAPI CD burner, you will have to use
<command>cdrecord</command> to burn your
CDs. <command>cdrecord</command> is not part of the base system;
you must install it from either the port at <port>sysutils/cdrtools</port>
or the appropriate
package. Changes to the base system can cause binary versions of
this program to fail, possibly resulting in a
<quote>coaster</quote>. You should therefore either upgrade the
port when you upgrade your system, or if you are <link
linkend="stable">tracking -STABLE</link>, upgrade the port when a
new version becomes available.</para>
<para>While <command>cdrecord</command> has many options, basic usage
is even simpler than <command>burncd</command>. Burning an ISO 9660
image is done with:</para>
<screen>&prompt.root; <userinput>cdrecord <option>dev=</option><replaceable>device</replaceable> <replaceable>imagefile.iso</replaceable></userinput></screen>
<para>The tricky part of using <command>cdrecord</command> is finding
the <option>dev</option> to use. To find the proper setting, use
the <option>-scanbus</option> flag of <command>cdrecord</command>,
which might produce results like this:</para>
<indexterm>
<primary>CDROMs</primary>
<secondary>burning</secondary>
</indexterm>
<screen>&prompt.root; <userinput>cdrecord <option>-scanbus</option></userinput>
Cdrecord 1.9 (i386-unknown-freebsd4.2) Copyright (C) 1995-2000 J&ouml;rg Schilling
Using libscg version 'schily-0.1'
scsibus0:
0,0,0 0) 'SEAGATE ' 'ST39236LW ' '0004' Disk
0,1,0 1) 'SEAGATE ' 'ST39173W ' '5958' Disk
0,2,0 2) *
0,3,0 3) 'iomega ' 'jaz 1GB ' 'J.86' Removable Disk
0,4,0 4) 'NEC ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM
0,5,0 5) *
0,6,0 6) *
0,7,0 7) *
scsibus1:
1,0,0 100) *
1,1,0 101) *
1,2,0 102) *
1,3,0 103) *
1,4,0 104) *
1,5,0 105) 'YAMAHA ' 'CRW4260 ' '1.0q' Removable CD-ROM
1,6,0 106) 'ARTEC ' 'AM12S ' '1.06' Scanner
1,7,0 107) *</screen>
<para>This lists the appropriate <option>dev</option> value for the
devices on the list. Locate your CD burner, and use the three
numbers separated by commas as the value for
<option>dev</option>. In this case, the CRW device is 1,5,0, so the
appropriate input would be
<userinput><option>dev</option>=1,5,0</userinput>. There are easier
ways to specify this value; see &man.cdrecord.1; for
details. That is also the place to look for information on writing
audio tracks, controlling the speed, and other things.</para>
</sect2>
<sect2 id="imaging-cd">
<title>Duplicating Data CDs</title>
<para>You can copy a data CD to a image file that is
functionally equivalent to the image file created with
<command>mkisofs</command>, and you can use it to duplicate
any data CD. The example given here assumes that your CDROM
device is <devicename>acd0</devicename>. Substitute your
correct CDROM device. A <literal>c</literal> must be appended
to the end of the device name to indicate the entire partition
or, in the case of CDROMs, the entire disc.</para>
<screen>&prompt.root; <userinput>dd if=/dev/acd0c of=file.iso bs=2048</userinput></screen>
<para>Now that you have an image, you can burn it to CD as
described above.</para>
<para>This does not work with audio CDs.</para>
</sect2>
<sect2 id="mounting-cd">
<title>Using Data CDs</title>
<para>Now that you have created a standard data CDROM, you
probably want to mount it and read the data on it. By
default, &man.mount.8; assumes that a filesystem is of type
<literal>ufs</literal>. If you try something like:</para>
<screen>&prompt.root; <userinput>mount /dev/cd0c/mnt</userinput></screen>
<para>you will get a complaint about <errorname>Incorrect super
block</errorname>, and no mount. The CDROM is not a
<literal>UFS</literal> filesystem, so attempts to mount it
as such will fail. You just need to tell &man.mount.8; that
the filesystem is of type <literal>ISO9660</literal>, and
everything will work. You do this by specifying the
<option>-t cd9660</option> option &man.mount.8;. For
example, if you want to mount the CDROM device,
<devicename>/dev/cd0c</devicename>, under
<filename>/mnt</filename>, you would execute:</para>
<screen>&prompt.root; <userinput>mount -t cd9660 /dev/cd0c /mnt</userinput></screen>
<para>Note that your device name
(<devicename>/dev/cd0c</devicename> in this example) could be
different, depending on the interface your CDROM uses. Also,
the <option>-t cd9660</option> option just executes
&man.mount.cd9660.8;. The above example could be shortened
to:</para>
<screen>&prompt.root; <userinput>mount_cd9660 /dev/cd0c /mnt</userinput></screen>
<para>You can generally use data CDROMs from any vendor in this
way. Disks with certain ISO 9660 extensions might behave
oddly, however. For example, Joliet disks store all filenames
in two-byte Unicode characters. The FreeBSD kernel does not
speak Unicode (yet!), so non-English characters show up as
question marks. (If you are running FreeBSD 4.3 or later, the
CD9660 driver includes hooks to load an appropriate Unicode
conversion table on the fly. Modules for some of the common
encodings are available via the
<port>sysutils/cd9660_unicode</port> port.)</para>
<para>Occasionally, you might get <errorname>Device not
configured</errorname> when trying to mount a CDROM. This
usually means that the CDROM drive thinks that there is no
disk in the tray, or that the drive is not visible on the bus.
It can take a couple of seconds for a CDROM drive to realize
that it has been fed, so be patient.</para>
<para>Sometimes, a SCSI CDROM may be missed because it didn't
have enough time to answer the bus reset. If you have a SCSI
CDROM please add the following option to your kernel
configuration and rebuild your kernel.</para>
<programlisting>options SCSI_DELAY=15000</programlisting>
<para>This tells your SCSI bus to pause 15 seconds during boot,
to give your CDROM drive every possible chance to answer the
bus reset.</para>
</sect2>
<sect2 id="rawdata-cd">
<title>Burning Raw Data CDs</title>
<para>You can choose to burn a file directly to CD, without
creating an ISO 9660 filesystem. Some people do this for
backup purposes. This runs more quickly than burning a
standard CD:</para>
<screen>&prompt.root; <userinput>burncd -f /dev/acd1c -s 12 data archive.tar.gz fixate</userinput></screen>
<para>In order to retrieve the data burned to such a CD, you
must read data from the raw device node :</para>
<screen>&prompt.root; <userinput>tar xzvf /dev/acd1c</userinput></screen>
<para>You cannot mount this disk as you would a normal CDROM.
Such a CDROM cannot be read under any operating system
except FreeBSD. If you want to be able to mount the CD, or
share data with another operating system, you must use
<port>sysutils/mkisofs</port> as described above.</para>
</sect2>
</sect1>
<sect1 id="raid">
<title>RAID</title>
<sect2 id="raid-soft">
<title>Software RAID</title>
<sect3 id="ccd">
<sect3info>
<authorgroup>
<author>
<firstname>Christopher</firstname>
<surname>Shumway</surname>
<contrib>Written by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Valentino</firstname>
<surname>Vaschetto</surname>
<contrib>Marked up by </contrib>
</author>
</authorgroup>
</sect3info>
<title>ccd (Concatenated Disk Configuration)</title>
<para>It seems like today everyone has a collection of
multimedia files. Everything from mp3's to video clips. I have
converted most of my audio CDROM collection to mp3's so I can
have all of my music in one centralized location, and not have
to hunt down the audio CD with that one song I got stuck in my
head. The problem I was faced with is where to store all
these files?</para>
<para>When choosing a mass storage solution, the most important
factors to consider are speed, reliability, and cost. It is very
rare to have all three in favor, normally a fast, reliable mass
storage device is expensive, and to cut back on cost either speed
or reliability must be sacrificed. In designing my system, I
ranked the requirements by most favorable to least favorable. In
this situation, cost was the biggest factor. I needed a lot of
storage for a reasonable price. The next factor, speed, is not
quite as important, since most of the usage would be over a one
hundred megabit switched Ethernet, and that would most likely be
the bottleneck. The ability to spread the file input/output
operations out over several disks would be more than enough speed
for this network. Finally, the consideration of reliability was
an easy one to answer. All of the data being put on this mass
storage device was already backed up on CD-R's. This drive was
primarily here for online live storage for easy access, so if a
drive went bad, I could just replace it, rebuild the filesystem,
and copy back the data from CD-R's.</para>
<para>To sum it up, I need something that will give me the most
amount of storage space for my money. The cost of large IDE disks
are cheap these days. I found a place that was selling Western
Digital 30.7gb 5400 RPM IDE disks for about one-hundred and thirty
US dollars. I bought three of them, giving me approximately
ninety gigabytes of online storage.</para>
<sect4 id="ccd-installhw">
<title>Installing the Hardware</title>
<para>I installed the hard drives in a system that already
had one IDE disk in as the system disk. The ideal solution
would be for each IDE disk to have its own IDE controller
and cable, but without fronting more costs to acquire a dual
IDE controller this would not be a possibility. So, I
jumpered two disks as slaves, and one as master. One went
on the first IDE controller as a slave to the system disk,
and the other two where slave/master on the secondary IDE
controller.</para>
<para>Upon reboot, the system BIOS was configured to
automatically detect the disks attached. More importantly,
FreeBSD detected them on reboot:</para>
<programlisting>ad0: 19574MB &lt;WDC WD205BA&gt; [39770/16/63] at ata0-master UDMA33
ad1: 29333MB &lt;WDC WD307AA&gt; [59598/16/63] at ata0-slave UDMA33
ad2: 29333MB &lt;WDC WD307AA&gt; [59598/16/63] at ata1-master UDMA33
ad3: 29333MB &lt;WDC WD307AA&gt; [59598/16/63] at ata1-slave UDMA33</programlisting>
<para>At this point, if FreeBSD does not detect the disks, be
sure that you have jumpered them correctly. I have heard
numerous reports with problems using cable select instead of
true slave/master configuration.</para>
<para>The next consideration was how to attach them as part of
the filesystem. I did a little research on <ulink
url="http://www.vinumvm.org/">&man.vinum.8;</ulink> and FreeBSD's
&man.ccd.4;. In this particular configuration, &man.ccd.4;
appeared to be a better choice mainly because it has fewer
parts. Less parts tends to indicate less chance of breakage.
Vinum appears to be a bit of an overkill for my needs.</para>
</sect4>
<sect4 id="ccd-setup">
<title>Setting up the CCD</title>
<para><application>CCD</application> allows me to take
several identical disks and concatenate them into one
logical filesystem. In order to use
<application>ccd</application>, I need a kernel with
<application>ccd</application> support built into it. I
added this line to my kernel configuration file and rebuilt
the kernel:</para>
<programlisting>pseudo-device ccd 4</programlisting>
<para><application>ccd</application> support can also be
loaded as a kernel loadable module in FreeBSD 4.0 or
later.</para>
<para>To set up <application>ccd</application>, first I need
to disklabel the disks. Here is how I disklabeled
them:</para>
<programlisting>disklabel -r -w ad1 auto
disklabel -r -w ad2 auto
disklabel -r -w ad3 auto</programlisting>
<para>This created a disklabel ad1c, ad2c and ad3c that
spans the entire disk.</para>
<para>The next step is to change the disklabel type. To do
that I had to edit the disklabel:</para>
<programlisting>disklabel -e ad1
disklabel -e ad2
disklabel -e ad3</programlisting>
<para>This opened up the current disklabel on each disk
respectively in whatever editor the <envar>EDITOR</envar>
environment variable was set to, in my case, &man.vi.1;.
Inside the editor I had a section like this:</para>
<programlisting>8 partitions:
# size offset fstype [fsize bsize bps/cpg]
c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597)</programlisting>
<para>I needed to add a new "e" partition for &man.ccd.4; to
use. This usually can be copied of the "c" partition, but
the <option>fstype</option> must be <userinput>4.2BSD</userinput>.
Once I was done,
my disklabel should look like this:</para>
<programlisting>8 partitions:
# size offset fstype [fsize bsize bps/cpg]
c: 60074784 0 unused 0 0 0 # (Cyl. 0 - 59597)
e: 60074784 0 4.2BSD 0 0 0 # (Cyl. 0 - 59597)</programlisting>
</sect4>
<sect4 id="ccd-buildingfs">
<title>Building the Filesystem</title>
<para>Now that I have all of the disks labeled, I needed to
build the <application>ccd</application>. To do that, I
used a utility called &man.ccdconfig.8;.
<command>ccdconfig</command> takes several arguments, the
first argument being the device to configure, in this case,
<devicename>/dev/ccd0c</devicename>. The device node for
<devicename>ccd0c</devicename> may not exist yet, so to
create it, perform the following commands:</para>
<programlisting>cd /dev
sh MAKEDEV ccd0</programlisting>
<para>The next argument <command>ccdconfig</command> expects
is the interleave for the filesystem. The interleave
defines the size of a stripe in disk blocks, normally five
hundred and twelve bytes. So, an interleave of thirty-two
would be sixteen thousand three hundred and eighty-four
bytes.</para>
<para>After the interleave comes the flags for
<command>ccdconfig</command>. If you want to enable drive
mirroring, you can specify a flag here. In this
configuration, I am not mirroring the
<application>ccd</application>, so I left it as zero.</para>
<para>The final arguments to <command>ccdconfig</command>
are the devices to place into the array. Putting it all
together I get this command:</para>
<programlisting>ccdconfig ccd0 32 0 /dev/ad1e /dev/ad2e /dev/ad3e</programlisting>
<para>This configures the <application>ccd</application>.
I can now &man.newfs.8; the filesystem.</para>
<programlisting>newfs /dev/ccd0c</programlisting>
</sect4>
<sect4 id="ccd-auto">
<title>Making it all Automatic</title>
<para>Finally, if I want to be able to mount the
<application>ccd</application>, I need to
configure it first. I write out my current configuration to
<filename>/etc/ccd.conf</filename> using the following command:</para>
<programlisting>ccdconfig -g &gt; /etc/ccd.conf</programlisting>
<para>When I reboot, the script <command>/etc/rc</command>
runs <command>ccdconfig -C</command> if /etc/ccd.conf
exists. This automatically configures the
<application>ccd</application> so it can be mounted.</para>
<para>If you are booting into single user mode, before you can
<command>mount</command> the <application>ccd</application>, you
need to issue the following command to configure the
array:</para>
<programlisting>ccdconfig -C</programlisting>
<para>Then, we need an entry for the
<application>ccd</application> in
<filename>/etc/fstab</filename> so it will be mounted at
boot time.</para>
<programlisting>/dev/ccd0c /media ufs rw 2 2</programlisting>
</sect4>
</sect3>
<sect3 id="vinum">
<title>vinum (Logical Volume Manager)</title>
<para>XXX</para>
</sect3>
</sect2>
<sect2 id="raid-hard">
<title>Hardware RAID</title>
<indexterm>
<primary>RAID</primary>
<secondary>Hardware</secondary>
</indexterm>
<para>FreeBSD supports a wide variety of hardware RAID
controllers from many popular manufacturers such as Adaptec,
3Ware, Mylex, DPT, AMI, Dell, HP, IBM, and more. The list of
supported adapters is growing all the time, so make sure to
check the release notes for complete information.
</para>
</sect2>
</sect1>
<sect1 id="backups-tapebackups">
<title>Tape Backup Media</title>
<indexterm><primary>tape media</primary></indexterm>
<para>The major tape media are the 4mm, 8mm, QIC, mini-cartridge and
DLT.</para>
<sect2 id="backups-tapebackups-4mm">
<title>4mm (DDS: Digital Data Storage)</title>
<indexterm>
<primary>tape media</primary>
<secondary>DDS (4mm) tapes</secondary>
</indexterm>
<indexterm>
<primary>tape media</primary>
<secondary>QIC tapes</secondary>
</indexterm>
<para>4mm tapes are replacing QIC as the workstation backup media of
choice. This trend accelerated greatly when Conner purchased Archive,
a leading manufacturer of QIC drives, and then stopped production of
QIC drives. 4mm drives are small and quiet but do not have the
reputation for reliability that is enjoyed by 8mm drives. The
cartridges are less expensive and smaller (3 x 2 x 0.5 inches, 76 x 51
x 12 mm) than 8mm cartridges. 4mm, like 8mm, has comparatively short
head life for the same reason, both use helical scan.</para>
<para>Data throughput on these drives starts ~150kB/s, peaking at ~500kB/s.
Data capacity starts at 1.3 GB and ends at 2.0 GB. Hardware
compression, available with most of these drives, approximately
doubles the capacity. Multi-drive tape library units can have 6
drives in a single cabinet with automatic tape changing. Library
capacities reach 240 GB.</para>
<para>The DDS-3 standard now supports tape capacities up to 12 GB (or
24 GB compressed).</para>
<para>4mm drives, like 8mm drives, use helical-scan. All the benefits
and drawbacks of helical-scan apply to both 4mm and 8mm drives.</para>
<para>Tapes should be retired from use after 2,000 passes or 100 full
backups.</para>
</sect2>
<sect2 id="backups-tapebackups-8mm">
<title>8mm (Exabyte)</title>
<indexterm>
<primary>tape media</primary>
<secondary>Exabyte (8mm) tapes</secondary>
</indexterm>
<para>8mm tapes are the most common SCSI tape drives; they are the best
choice of exchanging tapes. Nearly every site has an Exabyte 2 GB 8mm
tape drive. 8mm drives are reliable, convenient and quiet. Cartridges
are inexpensive and small (4.8 x 3.3 x 0.6 inches; 122 x 84 x 15 mm).
One downside of 8mm tape is relatively short head and tape life due to
the high rate of relative motion of the tape across the heads.</para>
<para>Data throughput ranges from ~250kB/s to ~500kB/s. Data sizes start
at 300 MB and go up to 7 GB. Hardware compression, available with
most of these drives, approximately doubles the capacity. These
drives are available as single units or multi-drive tape libraries
with 6 drives and 120 tapes in a single cabinet. Tapes are changed
automatically by the unit. Library capacities reach 840+ GB.</para>
<para>The Exabyte <quote>Mammoth</quote> model supports 12 GB on one tape
(24 GB with compression) and costs approximately twice as much as
conventional tape drives.</para>
<para>Data is recorded onto the tape using helical-scan, the heads are
positioned at an angle to the media (approximately 6 degrees). The
tape wraps around 270 degrees of the spool that holds the heads. The
spool spins while the tape slides over the spool. The result is a
high density of data and closely packed tracks that angle across the
tape from one edge to the other.</para>
</sect2>
<sect2 id="backups-tapebackups-qic">
<title>QIC</title>
<indexterm>
<primary>tape media</primary>
<secondary>QIC-150</secondary>
</indexterm>
<para>QIC-150 tapes and drives are, perhaps, the most common tape drive
and media around. QIC tape drives are the least expensive "serious"
backup drives. The downside is the cost of media. QIC tapes are
expensive compared to 8mm or 4mm tapes, up to 5 times the price per GB
data storage. But, if your needs can be satisfied with a half-dozen
tapes, QIC may be the correct choice. QIC is the
<emphasis>most</emphasis> common tape drive. Every site has a QIC
drive of some density or another. Therein lies the rub, QIC has a
large number of densities on physically similar (sometimes identical)
tapes. QIC drives are not quiet. These drives audibly seek before
they begin to record data and are clearly audible whenever reading,
writing or seeking. QIC tapes measure (6 x 4 x 0.7 inches; 15.2 x
10.2 x 1.7 mm). <link
linkend="backups-tapebackups-mini">Mini-cartridges</link>, which
also use 1/4" wide tape are discussed separately. Tape libraries and
changers are not available.</para>
<para>Data throughput ranges from ~150kB/s to ~500kB/s. Data capacity
ranges from 40 MB to 15 GB. Hardware compression is available on many
of the newer QIC drives. QIC drives are less frequently installed;
they are being supplanted by DAT drives.</para>
<para>Data is recorded onto the tape in tracks. The tracks run along
the long axis of the tape media from one end to the other. The number
of tracks, and therefore the width of a track, varies with the tape's
capacity. Most if not all newer drives provide backward-compatibility
at least for reading (but often also for writing). QIC has a good
reputation regarding the safety of the data (the mechanics are simpler
and more robust than for helical scan drives).</para>
<para>Tapes should be retired from use after 5,000 backups.</para>
</sect2>
<sect2 id="backups-tapebackups-mini">
<title>XXX* Mini-Cartridge</title>
<para></para>
</sect2>
<sect2 id="backups-tapebackups-dlt">
<title>DLT</title>
<indexterm>
<primary>tape media</primary>
<secondary>DLT</secondary>
</indexterm>
<para>DLT has the fastest data transfer rate of all the drive types
listed here. The 1/2" (12.5mm) tape is contained in a single spool
cartridge (4 x 4 x 1 inches; 100 x 100 x 25 mm). The cartridge has a
swinging gate along one entire side of the cartridge. The drive
mechanism opens this gate to extract the tape leader. The tape leader
has an oval hole in it which the drive uses to "hook" the tape. The
take-up spool is located inside the tape drive. All the other tape
cartridges listed here (9 track tapes are the only exception) have
both the supply and take-up spools located inside the tape cartridge
itself.</para>
<para>Data throughput is approximately 1.5MB/s, three times the throughput of
4mm, 8mm, or QIC tape drives. Data capacities range from 10 GB to 20 GB
for a single drive. Drives are available in both multi-tape changers
and multi-tape, multi-drive tape libraries containing from 5 to 900
tapes over 1 to 20 drives, providing from 50 GB to 9 TB of
storage.</para>
<para>With compression, DLT Type IV format supports up to 70 GB
capacity.</para>
<para>Data is recorded onto the tape in tracks parallel to the direction
of travel (just like QIC tapes). Two tracks are written at once.
Read/write head lifetimes are relatively long; once the tape stops
moving, there is no relative motion between the heads and the
tape.</para>
</sect2>
<sect2>
<title id="backups-tapebackups-ait">AIT</title>
<indexterm>
<primary>tape media</primary>
<secondary>AIT</secondary>
</indexterm>
<para>AIT is a new format from Sony, and can hold up to 50 GB (with
compression) per tape. The tapes contain memory chips which retain an
index of the tape's contents. This index can be rapidly read by the
tape drive to determine the position of files on the tape, instead of
the several minutes that would be required for other tapes. Software
such as SAMS:Alexandria can operate forty or more AIT tape libraries,
communicating directly with the tape's memory chip to display the
contents on screen, determine what files were backed up to which
tape, locate the correct tape, load it, and restore the data from the
tape.</para>
<para>Libraries like this cost in the region of $20,000, pricing them a
little out of the hobbyist market.</para>
</sect2>
<sect2>
<title>Using a New Tape for the First Time</title>
<para>The first time that you try to read or write a new, completely
blank tape, the operation will fail. The console messages should be
similar to:</para>
<screen>sa0(ncr1:4:0): NOT READY asc:4,1
sa0(ncr1:4:0): Logical unit is in process of becoming ready</screen>
<para>The tape does not contain an Identifier Block (block number 0).
All QIC tape drives since the adoption of QIC-525 standard write an
Identifier Block to the tape. There are two solutions:</para>
<para><command>mt fsf 1</command> causes the tape drive to write an
Identifier Block to the tape.</para>
<para>Use the front panel button to eject the tape.</para>
<para>Re-insert the tape and <command>dump</command> data to the tape.</para>
<para><command>dump</command> will report <literal>DUMP: End of tape
detected</literal> and the console will show: <literal>HARDWARE
FAILURE info:280 asc:80,96</literal>.</para>
<para>rewind the tape using: <command>mt rewind</command>.</para>
<para>Subsequent tape operations are successful.</para>
</sect2>
</sect1>
<sect1 id="backup-programs">
<title>Backup Programs</title>
<indexterm><primary>backup software</primary></indexterm>
<para>The three major programs are
&man.dump.8;,
&man.tar.1;,
and
&man.cpio.1;.</para>
<sect2>
<title>Dump and Restore</title>
<indexterm>
<primary>backup software</primary>
<secondary>dump / restore</secondary>
</indexterm>
<indexterm><primary><command>dump</command></primary></indexterm>
<indexterm><primary><command>restore</command></primary></indexterm>
<para>The traditional Unix backup programs are
<command>dump</command> and <command>restore</command>. They
operate on the drive as a collection of disk blocks, below the
abstractions of files, links and directories that are created by
the filesystems. <command>dump</command> backs up an entire
filesystem on a device. It is unable to backup only part of a
filesystem or a directory tree that spans more than one
filesystem. <command>dump</command> does not write files and
directories to tape, but rather writes the raw data blocks that
comprise files and directories.</para>
<note><para>If you use <command>dump</command> on your root directory, you
would not back up <filename>/home</filename>,
<filename>/usr</filename> or many other directories since
these are typically mount points for other filesystems or
symbolic links into those filesystems.</para></note>
<para><command>dump</command>has quirks that remain from its early days in
Version 6 of AT&amp;T Unix (circa 1975). The default
parameters are suitable for 9-track tapes (6250 bpi), not the
high-density media available today (up to 62,182 ftpi). These
defaults must be overridden on the command line to utilize the
capacity of current tape drives.</para>
<indexterm><primary><filename>rhosts</filename></primary></indexterm>
<para>It is also possible to backup data across the network to a
tape drive attached to another computer with <command>rdump</command> and
<command>rrestore</command>. Both programs rely upon <command>rcmd</command> and
<command>ruserok</command> to access the remote tape drive. Therefore,
the user performing the backup must have
<literal>rhosts</literal> access to the remote computer. The
arguments to <command>rdump</command> and <command>rrestore</command> must be suitable
to use on the remote computer. (e.g. When
<command>rdump</command>ing from a FreeBSD computer to an
Exabyte tape drive connected to a Sun called
<hostid>komodo</hostid>, use: <command>/sbin/rdump 0dsbfu
54000 13000 126 komodo:/dev/nrsa8 /dev/rda0a
2>&amp;1</command>) Beware: there are security implications to
allowing <literal>rhosts</literal> commands. Evaluate your
situation carefully.</para>
<para>It is also possible to use <command>rdump</command> and
<command>rrestore</command> in a more secure fashion over
<command>ssh</command>.</para>
<example>
<title>Using <command>rdump</command> over <application>ssh</application></title>
<screen>&prompt.root; <userinput>/sbin/dump -0uan -f - /usr | gzip -2 | ssh1 -c blowfish \
targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz</userinput></screen>
</example>
</sect2>
<sect2>
<title><command>tar</command></title>
<indexterm>
<primary>backup software</primary>
<secondary><command>tar</command></secondary>
</indexterm>
<para>&man.tar.1; also dates back to Version 6 of AT&amp;T Unix
(circa 1975). <command>tar</command> operates in cooperation
with the filesystem; <command>tar</command> writes files and
directories to tape. <command>tar</command> does not support the
full range of options that are available from &man.cpio.1;, but
<command>tar</command> does not require the unusual command
pipeline that <command>cpio</command> uses.</para>
<indexterm><primary><command>tar</command></primary></indexterm>
<para>Most versions of <command>tar</command> do not support
backups across the network. The GNU version of
<command>tar</command>, which FreeBSD utilizes, supports remote
devices using the same syntax as <command>rdump</command>. To
<command>tar</command> to an Exabyte tape drive connected to a
Sun called <hostid>komodo</hostid>, use: <command>/usr/bin/tar
cf komodo:/dev/nrsa8 . 2>&amp;1</command>. For versions without
remote device support, you can use a pipeline and
<command>rsh</command> to send the data to a remote tape
drive.</para>
<screen>&prompt.root; <userinput>tar cf - . | rsh <replaceable>hostname</replaceable> dd of=<replaceable>tape-device</replaceable> obs=20b</userinput></screen>
<para>If you are worried about the security of backing up over a
network you should use the <command>ssh</command> command
instead of <command>rsh</command>.</para>
</sect2>
<sect2>
<title><command>cpio</command></title>
<indexterm>
<primary>backup software</primary>
<secondary><command>cpio</command></secondary>
</indexterm>
<para>&man.cpio.1; is the original Unix file interchange tape
program for magnetic media. <command>cpio</command> has options
(among many others) to perform byte-swapping, write a number of
different archive formats, and pipe the data to other programs.
This last feature makes <command>cpio</command> and excellent
choice for installation media. <command>cpio</command> does not
know how to walk the directory tree and a list of files must be
provided through <filename>stdin</filename>.</para>
<indexterm><primary><command>cpio</command></primary></indexterm>
<para><command>cpio</command> does not support backups across
the network. You can use a pipeline and <command>rsh</command>
to send the data to a remote tape drive.</para>
<screen>&prompt.root; <userinput>for f in <replaceable>directory_list; do</replaceable></userinput>
<userinput>find $f >> backup.list</userinput>
<userinput>done</userinput>
&prompt.root; <userinput>cpio -v -o --format=newc < backup.list | ssh <replaceable>user</replaceable>@<replaceable>host</replaceable> "cat > <replaceable>backup_device</replaceable>"</userinput></screen>
<para>Where <replaceable>directory_list</replaceable> is the list of
directories you want to back up,
<replaceable>user</replaceable>@<replaceable>host</replaceable> is the
user/hostname combination that will be performing the backups, and
<replaceable>backup_device</replaceable> is where the backups should
be written to (e.g., <filename>/dev/nrsa0</filename>).</para>
</sect2>
<sect2>
<title><command>pax</command></title>
<indexterm>
<primary>backup software</primary>
<secondary><command>pax</command></secondary>
</indexterm>
<indexterm><primary><command>pax</command></primary></indexterm>
<indexterm><primary>POSIX</primary></indexterm>
<indexterm><primary>IEEE</primary></indexterm>
<para>&man.pax.1; is IEEE/POSIX's answer to
<command>tar</command> and <command>cpio</command>. Over the
years the various versions of <command>tar</command> and
<command>cpio</command> have gotten slightly incompatible. So
rather than fight it out to fully standardize them, POSIX
created a new archive utility. <command>pax</command> attempts
to read and write many of the various <command>cpio</command>
and <command>tar</command> formats, plus new formats of its own.
Its command set more resembles <command>cpio</command> than
<command>tar</command>.</para>
</sect2>
<sect2 id="backups-programs-amanda">
<title><application>Amanda</application></title>
<indexterm>
<primary>backup software</primary>
<secondary><application>Amanda</application></secondary>
</indexterm>
<indexterm><primary><application>Amanda</application></primary></indexterm>
<!-- Remove link until <port> tag is available -->
<para><application>Amanda</application> (Advanced Maryland
Network Disk Archiver) is a client/server backup system,
rather than a single program. An Amanda server will backup to
a single tape drive any number of computers that have Amanda
clients and a network connection to the Amanda server. A
common problem at sites with a number of large disks is
that the length of time required to backup to data directly to tape
exceeds the amount of time available for the task. Amanda
solves this problem. Amanda can use a "holding disk" to
backup several filesystems at the same time. Amanda creates
"archive sets": a group of tapes used over a period of time to
create full backups of all the filesystems listed in Amanda's
configuration file. The "archive set" also contains nightly
incremental (or differential) backups of all the filesystems.
Restoring a damaged filesystem requires the most recent full
backup and the incremental backups.</para>
<para>The configuration file provides fine control of backups and the
network traffic that Amanda generates. Amanda will use any of the
above backup programs to write the data to tape. Amanda is available
as either a port or a package, it is not installed by default.</para>
</sect2>
<sect2>
<title>Do Nothing</title>
<para><quote>Do nothing</quote> is not a computer program, but it is the
most widely used backup strategy. There are no initial costs. There
is no backup schedule to follow. Just say no. If something happens
to your data, grin and bear it!</para>
<para>If your time and your data is worth little to nothing, then
<quote>Do nothing</quote> is the most suitable backup program for your
computer. But beware, Unix is a useful tool, you may find that within
six months you have a collection of files that are valuable to
you.</para>
<para><quote>Do nothing</quote> is the correct backup method for
<filename>/usr/obj</filename> and other directory trees that can be
exactly recreated by your computer. An example is the files that
comprise the HTML or Postscript version of this Handbook.
These document formats have been created from SGML input
files. Creating backups of the HTML or PostScript files is
not necessary. The SGML files are backed up regularly.</para>
</sect2>
<sect2>
<title>Which Backup Program Is Best?</title>
<indexterm>
<primary>LISA</primary>
</indexterm>
<para>&man.dump.8; <emphasis>Period.</emphasis> Elizabeth D. Zwicky
torture tested all the backup programs discussed here. The clear
choice for preserving all your data and all the peculiarities of Unix
filesystems is <command>dump</command>. Elizabeth created filesystems containing
a large variety of unusual conditions (and some not so unusual ones)
and tested each program by doing a backup and restore of those
filesystems. The peculiarities included: files with holes, files with
holes and a block of nulls, files with funny characters in their
names, unreadable and unwritable files, devices, files that change
size during the backup, files that are created/deleted during the
backup and more. She presented the results at LISA V in Oct. 1991.
See <ulink
url="http://reality.sgi.com/zwicky_neu/testdump.doc.html">torture-testing
Backup and Archive Programs</ulink>.</para>
</sect2>
<sect2>
<title>Emergency Restore Procedure</title>
<sect3>
<title>Before the Disaster</title>
<para>There are only four steps that you need to perform in
preparation for any disaster that may occur.</para>
<indexterm>
<primary><command>disklabel</command></primary>
</indexterm>
<para>First, print the disklabel from each of your disks
(<command>e.g. disklabel da0 | lpr</command>), your filesystem table
(<filename>/etc/fstab</filename>) and all boot messages,
two copies of
each.</para>
<indexterm><primary>fix-it floppies</primary></indexterm>
<para>Second, determine that the boot and fix-it floppies
(<filename>boot.flp</filename> and <filename>fixit.flp</filename>)
have all your devices. The easiest way to check is to reboot your
machine with the boot floppy in the floppy drive and check the boot
messages. If all your devices are listed and functional, skip on to
step three.</para>
<para>Otherwise, you have to create two custom bootable
floppies which have a kernel that can mount all of your disks
and access your tape drive. These floppies must contain:
<command>fdisk</command>, <command>disklabel</command>,
<command>newfs</command>, <command>mount</command>, and
whichever backup program you use. These programs must be
statically linked. If you use <command>dump</command>, the
floppy must contain <command>restore</command>.</para>
<para>Third, create backup tapes regularly. Any changes that you make
after your last backup may be irretrievably lost. Write-protect the
backup tapes.</para>
<para>Fourth, test the floppies (either <filename>boot.flp</filename>
and <filename>fixit.flp</filename> or the two custom bootable
floppies you made in step two.) and backup tapes. Make notes of the
procedure. Store these notes with the bootable floppy, the
printouts and the backup tapes. You will be so distraught when
restoring that the notes may prevent you from destroying your backup
tapes (How? In place of <command>tar xvf /dev/rsa0</command>, you
might accidently type <command>tar cvf /dev/rsa0</command> and
over-write your backup tape).</para>
<para>For an added measure of security, make bootable floppies and two
backup tapes each time. Store one of each at a remote location. A
remote location is NOT the basement of the same office building. A
number of firms in the World Trade Center learned this lesson the
hard way. A remote location should be physically separated from
your computers and disk drives by a significant distance.</para>
<example>
<title>A Script for Creating a Bootable Floppy</title>
<programlisting><![ CDATA [#!/bin/sh
#
# create a restore floppy
#
# format the floppy
#
PATH=/bin:/sbin:/usr/sbin:/usr/bin
fdformat -q fd0
if [ $? -ne 0 ]
then
echo "Bad floppy, please use a new one"
exit 1
fi
# place boot blocks on the floppy
#
disklabel -w -B /dev/fd0c fd1440
#
# newfs the one and only partition
#
newfs -t 2 -u 18 -l 1 -c 40 -i 5120 -m 5 -o space /dev/fd0a
#
# mount the new floppy
#
mount /dev/fd0a /mnt
#
# create required directories
#
mkdir /mnt/dev
mkdir /mnt/bin
mkdir /mnt/sbin
mkdir /mnt/etc
mkdir /mnt/root
mkdir /mnt/mnt # for the root partition
mkdir /mnt/tmp
mkdir /mnt/var
#
# populate the directories
#
if [ ! -x /sys/compile/MINI/kernel ]
then
cat << EOM
The MINI kernel does not exist, please create one.
Here is an example config file:
#
# MINI -- A kernel to get FreeBSD onto a disk.
#
machine "i386"
cpu "I486_CPU"
ident MINI
maxusers 5
options INET # needed for _tcp _icmpstat _ipstat
# _udpstat _tcpstat _udb
options FFS #Berkeley Fast File System
options FAT_CURSOR #block cursor in syscons or pccons
options SCSI_DELAY=15 #Be pessimistic about Joe SCSI device
options NCONS=2 #1 virtual consoles
options USERCONFIG #Allow user configuration with -c XXX
config kernel root on da0 swap on da0 and da1 dumps on da0
device isa0
device pci0
device fdc0 at isa? port "IO_FD1" bio irq 6 drq 2 vector fdintr
device fd0 at fdc0 drive 0
device ncr0
device scbus0
device sc0 at isa? port "IO_KBD" tty irq 1 vector scintr
device npx0 at isa? port "IO_NPX" irq 13 vector npxintr
device da0
device da1
device da2
device sa0
pseudo-device loop # required by INET
pseudo-device gzip # Exec gzipped a.out's
EOM
exit 1
fi
cp -f /sys/compile/MINI/kernel /mnt
gzip -c -best /sbin/init > /mnt/sbin/init
gzip -c -best /sbin/fsck > /mnt/sbin/fsck
gzip -c -best /sbin/mount > /mnt/sbin/mount
gzip -c -best /sbin/halt > /mnt/sbin/halt
gzip -c -best /sbin/restore > /mnt/sbin/restore
gzip -c -best /bin/sh > /mnt/bin/sh
gzip -c -best /bin/sync > /mnt/bin/sync
cp /root/.profile /mnt/root
cp -f /dev/MAKEDEV /mnt/dev
chmod 755 /mnt/dev/MAKEDEV
chmod 500 /mnt/sbin/init
chmod 555 /mnt/sbin/fsck /mnt/sbin/mount /mnt/sbin/halt
chmod 555 /mnt/bin/sh /mnt/bin/sync
chmod 6555 /mnt/sbin/restore
#
# create the devices nodes
#
cd /mnt/dev
./MAKEDEV std
./MAKEDEV da0
./MAKEDEV da1
./MAKEDEV da2
./MAKEDEV sa0
./MAKEDEV pty0
cd /
#
# create minimum filesystem table
#
cat > /mnt/etc/fstab <<EOM
/dev/fd0a / ufs rw 1 1
EOM
#
# create minimum passwd file
#
cat > /mnt/etc/passwd <<EOM
root:*:0:0:Charlie &:/root:/bin/sh
EOM
cat > /mnt/etc/master.passwd <<EOM
root::0:0::0:0:Charlie &:/root:/bin/sh
EOM
chmod 600 /mnt/etc/master.passwd
chmod 644 /mnt/etc/passwd
/usr/sbin/pwd_mkdb -d/mnt/etc /mnt/etc/master.passwd
#
# umount the floppy and inform the user
#
/sbin/umount /mnt
echo "The floppy has been unmounted and is now ready."]]></programlisting>
</example>
</sect3>
<sect3>
<title>After the Disaster</title>
<para>The key question is: did your hardware survive? You have been
doing regular backups so there is no need to worry about the
software.</para>
<para>If the hardware has been damaged. First, replace those parts
that have been damaged.</para>
<para>If your hardware is okay, check your floppies. If you are using
a custom boot floppy, boot single-user (type <literal>-s</literal>
at the <prompt>boot:</prompt> prompt). Skip the following
paragraph.</para>
<para>If you are using the <filename>boot.flp</filename> and
<filename>fixit.flp</filename> floppies, keep reading. Insert the
<filename>boot.flp</filename> floppy in the first floppy drive and
boot the computer. The original install menu will be displayed on
the screen. Select the <literal>Fixit--Repair mode with CDROM or
floppy.</literal> option. Insert the
<filename>fixit.flp</filename> when prompted.
<command>restore</command> and the other programs that you need are
located in <filename>/mnt2/stand</filename>.</para>
<para>Recover each filesystem separately.</para>
<indexterm>
<primary><command>mount</command></primary>
</indexterm>
<indexterm><primary>root partition</primary></indexterm>
<indexterm>
<primary><command>disklabel</command></primary>
</indexterm>
<indexterm>
<primary><command>newfs</command></primary>
</indexterm>
<para>Try to <command>mount</command> (e.g. <command>mount /dev/da0a
/mnt</command>) the root partition of your first disk. If the
disklabel was damaged, use <command>disklabel</command> to re-partition and
label the disk to match the label that you printed and saved. Use
<command>newfs</command> to re-create the filesystems. Re-mount the root
partition of the floppy read-write (<command>mount -u -o rw
/mnt</command>). Use your backup program and backup tapes to
recover the data for this filesystem (e.g. <command>restore vrf
/dev/sa0</command>). Unmount the filesystem (e.g. <command>umount
/mnt</command>) Repeat for each filesystem that was
damaged.</para>
<para>Once your system is running, backup your data onto new tapes.
Whatever caused the crash or data loss may strike again. Another
hour spent now may save you from further distress later.</para>
</sect3>
<![ %not.published; [
<sect3>
<title>* I did not prepare for the Disaster, What Now?</title>
<para></para>
</sect3>
]]>
</sect2>
</sect1>
<sect1 id="floppies">
<sect1info>
<authorgroup>
<author>
<firstname>Julio</firstname>
<surname>Merino</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
<!-- 24 Dec 2001 -->
</sect1info>
<title>Floppy disks</title>
<para>Floppy disks are, nowadays, an old-fashioned medium to
store/share data. Although, there are still some times when you
need to use them, because you do not have any other removable
storage media or you need to use what you have saved in them on
any other computer.</para>
<para>This section will explain how to use floppy disks in
FreeBSD, that is, formating and copying/restoring data from
them. But... I really have written this to help you about how to
create forced-size floppies.</para>
<sect2>
<title>The device</title>
<para>Floppy disks are accessed throught entries in
<filename>/dev</filename> (like any other device). To access the
raw floppy disk you can use <filename>/dev/rfdX</filename>,
where X stands for the drive number, usually 0. When the disk is
formatted you can use <filename>/dev/fdX</filename>, or
whichever of the other devices named
<filename>/dev/fdXY</filename>, where Y stands for a
letter. These are all the same.</para>
<para>Other important devices are
<filename>/dev/fdX.size</filename>, where size is a floppy disk
size in kilobytes. These entries are used at low-level format
time to determine the disk size.</para>
<para>Sometimes you will have to (re)create these entries under
<filename>/dev</filename>. To do it, you can issue:</para>
<screen>&prompt.root; <userinput>cd /dev && ./MAKEDEV "fd*"</userinput></screen>
</sect2>
<sect2>
<title>Formatting</title>
<para>A floppy disk needs to be low-level formated before it can
be used. This is usually done by the vendor but you may want to
do it to check media integrity or to force the disk capacity to
be bigger.</para>
<para>To format the floppy at a low-level fashion you need to
use <application>fdformat</application>. This utility expects
the device name as an argument. We will use those
<filename>/dev/fdX.size</filename> devices, which will allow us
to format the floppy to its real size, or force them. So you
insert a new 3.5inch floppy disk in your drive and issue:</para>
<screen>&prompt.root; <userinput>/usr/sbin/fdformat /dev/rfd0.1440</userinput></screen>
<para>This will take a while... You should notice any disk error
here (this can help you determining which disks are good or
bad).</para>
<para>To force the floppy disk size, we will use other entries
in <filename>/dev</filename>. Get the same floppy and issue:
<screen>&prompt.root; <userinput>/usr/sbin/fdformat /dev/rfd0.1720</userinput></screen>
<para>It will take some more time than before (forced disks are
slower). When it finishes, you will have a 1720kb floppy disk,
but for the moment you will not notice any difference. You may
use other disk sizes that you can find in /dev, but the most
stable/compatible is the 1720kb for 3.5inch disks.</para>
</sect2>
<sect2>
<title>The disklabel</title>
<para>After low-level formatting the disk, you will need to
place a disklabel on it. This disklabel will be destroyed
later, but it is needed by the system to determine the size of
the disk and its geometry later.</para>
<para>The new disklabel will take over the whole disk, and will
contain all the proper information about the geometry of the
normal or forced floppy. Take a look to
<filename>/etc/disktab</filename> now; you will see geometry
values of all kinds of floppy disks.
<para>You can run now <application>disklabel</application>
like:</para>
<screen>&prompt.root; <userinput>/sbin/disklabel -B -r -w /dev/rfd0 fd(size)</userinput></screen>
<para>Replace fd(size) with fd1440, fd1720 or whichever size you
want. The last field instructs disklabel which entry to take
from <filename>/etc/disktab</filename> to use.</para>
</sect2>
<sect2>
<title>The filesystem</title>
<para>Now your floppy is ready to be high-level formated. This
will place a new filesystem on it, which will let FreeBSD read
and write to the disk. After creating the new filesystem, the
disklabel is destroyed, so if you want to reformat the disk, you
will have to recreate the disklabel another time.</para>
<para>You can choose now which filesystem to use on your floppy.
You can use UFS or FAT, though UFS is not a good idea for
floppies. Choose FAT which is nice for floppies.</para>
<para>To put a new filesystem on the floppy do this:</para>
<screen>&prompt.root; <userinput>/sbin/newfs_msdos /dev/fd0</userinput></screen>
<para>As we created a disklabel before, <application>newfs</application>
will be able to fetch disk data and construct the new
filesystem. And now, your disk is ready for use...</para>
</sect2>
<sect2>
<title>Using the floppy</title>
<para>You have two choices to use the floppy. You can either
mount the disk with <application>mount_msdos</application>, or you can
use <application>mtools</application>.
<application>Mtools</application> are great, but you will need
to install them from the ports system.</para>
<para>Try it; issue a <application>mdir</application>. If you forced the
disk, you will notice its extra size!</para>
<para>A last note about forced disks: they are compatible with
practically all other operating systems without any external
utility to read/write them. Microsoft systems will recognize
them without problems. But note that there may be times when the
floppy drive itself is not able to read them (this may happen
with very old drives).</para>
</sect2>
</sect1>
<sect1 id="backups-floppybackups">
<title>Backups to Floppies</title>
<sect2 id="floppies-using">
<title>Can I Use floppies for Backing Up My Data?</title>
<indexterm><primary>backup floppies</primary></indexterm>
<indexterm><primary>floppy disks</primary></indexterm>
<para>Floppy disks are not really a suitable media for
making backups as:</para>
<itemizedlist>
<listitem>
<para>The media is unreliable, especially over long periods of
time</para>
</listitem>
<listitem>
<para>Backing up and restoring is very slow</para>
</listitem>
<listitem>
<para>They have a very limited capacity (the days of backing up
an entire hard disk onto a dozen or so floppies has long since
passed).</para>
</listitem>
</itemizedlist>
<para>However, if you have no other method of backing up your data then
floppy disks are better than no backup at all.</para>
<para>If you do have to use floppy disks then ensure that you use good
quality ones. Floppies that have been lying around the office for a
couple of years are a bad choice. Ideally use new ones from a
reputable manufacturer.</para>
</sect2>
<sect2 id="floppies-creating">
<title>So How Do I Backup My Data to Floppies?</title>
<para>The best way to backup to floppy disk is to use
<command>tar</command> with the <option>-M</option> (multi
volume) option, which allows backups to span multiple
floppies.</para>
<para>To backup all the files in the current directory and sub-directory
use this (as root):</para>
<screen>&prompt.root; <userinput>tar Mcvf /dev/fd0 *</userinput></screen>
<para>When the first floppy is full <command>tar</command> will prompt you to
insert the next volume (because <command>tar</command> is media independent it
refers to volumes. In this context it means floppy disk)</para>
<screen>Prepare volume #2 for /dev/fd0 and hit return:</screen>
<para>This is repeated (with the volume number incrementing) until all
the specified files have been archived.</para>
</sect2>
<sect2 id="floppies-compress">
<title>Can I Compress My Backups?</title>
<indexterm>
<primary><command>tar</command></primary>
</indexterm>
<indexterm>
<primary><command>gzip</command></primary>
</indexterm>
<indexterm><primary>compression</primary></indexterm>
<para>Unfortunately, <command>tar</command> will not allow the
<option>-z</option> option to be used for multi-volume archives.
You could, of course, <command>gzip</command> all the files,
<command>tar</command> them to the floppies, then
<command>gunzip</command> the files again!</para>
</sect2>
<sect2 id="floppies-restoring">
<title>How Do I Restore My Backups?</title>
<para>To restore the entire archive use:</para>
<screen>&prompt.root; <userinput>tar Mxvf /dev/fd0</userinput></screen>
<para>There are two ways that you can use to restore only
specific files. First, you can start with the first floppy
and use:</para>
<screen>&prompt.root; <userinput>tar Mxvf /dev/fd0 <replaceable>filename</replaceable></userinput></screen>
<para><command>tar</command> will prompt you to insert subsequent floppies until it
finds the required file.</para>
<para>Alternatively, if you know which floppy the file is on then you
can simply insert that floppy and use the same command as above. Note
that if the first file on the floppy is a continuation from the
previous one then <command>tar</command> will warn you that it cannot
restore it, even if you have not asked it to!</para>
</sect2>
</sect1>
</chapter>
<!--
Local Variables:
mode: sgml
sgml-declaration: "../chapter.decl"
sgml-indent-data: t
sgml-omittag: nil
sgml-always-quote-attributes: t
sgml-parent-document: ("../book.sgml" "part" "chapter")
End:
-->
Reference in a new issue View git blame Copy permalink