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Finish the section about mdconfig(8); and mdmfs(8);. I also

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updated a bit the part about FreeBSD 4.X
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Marc Fonvieille 2002-12-08 15:59:18 +00:00
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Notes: svn2git 2020-12-08 03:00:23 +00:00 
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@ -2069,6 +2069,15 @@ echo "The floppy has been unmounted and is now ready."]]></programlisting>
</sect1> </sect1>
<sect1 id="disks-virtual"> <sect1 id="disks-virtual">
<sect1info>
<authorgroup>
<author>
<firstname>Marc</firstname>
<surname>Fonvieille</surname>
<contrib>Reorganized and enhanced by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Network, Memory, and File-Based File Systems</title> <title>Network, Memory, and File-Based File Systems</title>
<indexterm><primary>virtual disks</primary></indexterm> <indexterm><primary>virtual disks</primary></indexterm>
<indexterm> <indexterm>
@ -2096,14 +2105,21 @@ echo "The floppy has been unmounted and is now ready."]]></programlisting>
different tools for creation and use of file-backed and different tools for creation and use of file-backed and
memory-based file systems.</para> memory-based file systems.</para>
<note>
<para>The FreeBSD&nbsp;4.X users will have to use &man.MAKEDEV.8;
to create the required devices. FreeBSD&nbsp;5.0 and later use
&man.devfs.5; to allocate device nodes transparently for the
user.</para>
</note>
<sect2 id="disks-vnconfig"> <sect2 id="disks-vnconfig">
<title>File-Backed File System under FreeBSD&nbsp;4.X</title> <title>File-Backed File System under FreeBSD&nbsp;4.X</title>
<indexterm> <indexterm>
<primary>disks</primary> <primary>disks</primary>
<secondary>file-backed</secondary> <secondary>file-backed under FreeBSD&nbsp;4.X</secondary>
</indexterm> </indexterm>
<para>&man.vnconfig.8; configures and enables vnode pseudo-disk <para>The utility &man.vnconfig.8; configures and enables vnode pseudo-disk
devices. A <firstterm>vnode</firstterm> is a representation devices. A <firstterm>vnode</firstterm> is a representation
of a file, and is the focus of file activity. This means that of a file, and is the focus of file activity. This means that
&man.vnconfig.8; uses files to create and operate a &man.vnconfig.8; uses files to create and operate a
@ -2125,10 +2141,10 @@ echo "The floppy has been unmounted and is now ready."]]></programlisting>
&prompt.root; <userinput>mount /dev/vn<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput></screen> &prompt.root; <userinput>mount /dev/vn<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput></screen>
</example> </example>
<para>To create a new file system image with vnconfig:</para> <para>To create a new file system image with &man.vnconfig.8;:</para>
<example> <example>
<title>Creating a New File-Backed Disk with vnconfig</title> <title>Creating a New File-Backed Disk with <command>vnconfig</command></title>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=<replaceable>newimage</replaceable> bs=1k count=<replaceable>5</replaceable>k</userinput> <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 in
@ -2152,10 +2168,10 @@ Filesystem 1K-blocks Used Avail Capacity Mounted on
<title>File-Backed File System under FreeBSD&nbsp;5.X</title> <title>File-Backed File System under FreeBSD&nbsp;5.X</title>
<indexterm> <indexterm>
<primary>disks</primary> <primary>disks</primary>
<secondary>file-backed</secondary> <secondary>file-backed under FreeBSD&nbsp;5.X</secondary>
</indexterm> </indexterm>
<para>&man.mdconfig.8; is the utility used to configure and enable <para>The utility &man.mdconfig.8; is used to configure and enable
memory disks, &man.md.4;, under FreeBSD&nbsp;5.X. To use memory disks, &man.md.4;, under FreeBSD&nbsp;5.X. To use
&man.mdconfig.8;, you have to load &man.md.4; module or to add &man.mdconfig.8;, you have to load &man.md.4; module or to add
the support in your kernel configuration file:</para> the support in your kernel configuration file:</para>
@ -2171,17 +2187,17 @@ Filesystem 1K-blocks Used Avail Capacity Mounted on
<para>To mount an existing file system image:</para> <para>To mount an existing file system image:</para>
<example> <example>
<title>Using mdconfig to mount an Existing File System <title>Using <command>mdconfig</command> to mount an Existing File System
Image under FreeBSD&nbsp;5.X</title> Image under FreeBSD&nbsp;5.X</title>
<screen>&prompt.root; <userinput>mdconfig -a -t vnode -f <replaceable>diskimage</replaceable> -u <replaceable>0</replaceable></userinput> <screen>&prompt.root; <userinput>mdconfig -a -t vnode -f <replaceable>diskimage</replaceable> -u <replaceable>0</replaceable></userinput>
&prompt.root; <userinput>mount /dev/md<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput></screen> &prompt.root; <userinput>mount /dev/md<replaceable>0</replaceable>c <replaceable>/mnt</replaceable></userinput></screen>
</example> </example>
<para>To create a new file system image with mdconfig:</para> <para>To create a new file system image with &man.mdconfig.8;:</para>
<example> <example>
<title>Creating a New File-Backed Disk with mdconfig</title> <title>Creating a New File-Backed Disk with <command>mdconfig</command></title>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=<replaceable>newimage</replaceable> bs=1k count=<replaceable>5</replaceable>k</userinput> <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 in
@ -2199,6 +2215,13 @@ Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0c 4846 2 4458 0% /mnt</screen> /dev/md0c 4846 2 4458 0% /mnt</screen>
</example> </example>
<para>If you do not specify the unit number with the
<option>-u</option> option, &man.mdconfig.8; will use the
&man.md.4; automatic allocation to select an unused device.
The name of the allocated unit will be output on stdout like
<devicename>md4</devicename>. For more details about
&man.mdconfig.8;, please refer to the manual page.</para>
<para>The utility &man.mdconfig.8; is very useful, however it <para>The utility &man.mdconfig.8; is very useful, however it
asks many command lines to create a file-backed file system. asks many command lines to create a file-backed file system.
FreeBSD&nbsp;5.0 also comes with a tool called &man.mdmfs.8;, FreeBSD&nbsp;5.0 also comes with a tool called &man.mdmfs.8;,
@ -2208,28 +2231,38 @@ Filesystem 1K-blocks Used Avail Capacity Mounted on
if you want to create and mount the same file system image as if you want to create and mount the same file system image as
above, simply type the following:</para> above, simply type the following:</para>
<screen>&prompt.root; <userinput>mdmfs -F <replaceable>newimage</replaceable> -s <replaceable>5</replaceable>m md<replaceable>0</replaceable> <replaceable>/mnt</replaceable></userinput></screen> <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 in
5120+0 records out
&prompt.root; <userinput>mdmfs -F <replaceable>newimage</replaceable> -s <replaceable>5</replaceable>m md<replaceable>0</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>df <replaceable>/mnt</replaceable></userinput>
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0 4846 2 4458 0% /mnt</screen>
<para>For more details about &man.mdmfs.8;, please refer to <para>If you use the option <option>md</option> without unit
the manual page.</para> number, &man.mdmfs.8; will use &man.md.4; auto-unit feature to
automatically select an unused device. For more details
about &man.mdmfs.8;, please refer to the manual page.</para>
</sect2> </sect2>
<sect2 id="disks-md"> <sect2 id="disks-md-freebsd4">
<title>md: Memory File System</title> <title>Memory-Based File System under FreeBSD&nbsp;4.X</title>
<indexterm> <indexterm>
<primary>disks</primary> <primary>disks</primary>
<secondary>memory file system</secondary> <secondary>memory file system under FreeBSD&nbsp;4.X</secondary>
</indexterm> </indexterm>
<para><devicename>md</devicename> is a simple, efficient means to create memory <para>The &man.md.4; driver is a simple, efficient means to create memory
file systems.</para> file systems under FreeBSD&nbsp;4.X. &man.malloc.9; is used
to allocate the memory.</para>
<para>Simply take a file system you have prepared with, for <para>Simply take a file system you have prepared with, for
example, &man.vnconfig.8;, and:</para> example, &man.vnconfig.8;, and:</para>
<example> <example>
<title>md Memory Disk</title> <title>md Memory Disk under FreeBSD&nbsp;4.X</title>
<screen>&prompt.root; <userinput>dd if=<replaceable>newimage</replaceable> of=/dev/md<replaceable>0</replaceable></userinput> <screen>&prompt.root; <userinput>dd if=<replaceable>newimage</replaceable> of=/dev/md<replaceable>0</replaceable></userinput>
5120+0 records in 5120+0 records in
@ -2239,6 +2272,86 @@ Filesystem 1K-blocks Used Avail Capacity Mounted on
Filesystem 1K-blocks Used Avail Capacity Mounted on Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0c 4927 1 4532 0% /mnt</screen> /dev/md0c 4927 1 4532 0% /mnt</screen>
</example> </example>
<para>For more details, please refer to &man.md.4; manual
page.</para>
<sect2 id="disks-md-freebsd5">
<title>Memory-Based File System under FreeBSD&nbsp;5.X</title>
<indexterm>
<primary>disks</primary>
<secondary>memory file system under FreeBSD&nbsp;5.X</secondary>
</indexterm>
<para>The same tools are used for memory-based and file-backed
file systems: &man.mdconfig.8; or &man.mdmfs.8;. The storage
for memory-based file system is allocated with
&man.malloc.9;.</para>
<example>
<title>Creating a New Memory-Based Disk with
<command>mdconfig</command></title>
<screen>&prompt.root; <userinput>mdconfig -a -t malloc -s <replaceable>5</replaceable>m -u <replaceable>1</replaceable></userinput>
&prompt.root; <userinput>newfs -U md<replaceable>1</replaceable></userinput>
/dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048
using 4 cylinder groups of 1.27MB, 81 blks, 256 inodes.
with soft updates
super-block backups (for fsck -b #) at:
32, 2624, 5216, 7808
&prompt.root; <userinput>mount /dev/md<replaceable>1</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>df <replaceable>/mnt</replaceable></userinput>
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md1 4846 2 4458 0% /mnt</screen>
</example>
<example>
<title>Creating a New Memory-Based Disk with
<command>mdmfs</command></title>
<screen>&prompt.root; <userinput>mdmfs -M -s <replaceable>5</replaceable>m md<replaceable>2</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>df <replaceable>/mnt</replaceable></userinput>
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md2 4846 2 4458 0% /mnt</screen>
</example>
<para>Instead of using a &man.malloc.9; backed file system, it is
possible to use swap, for that just replace
<option>malloc</option> with <option>swap</option> in the
command line of &man.mdconfig.8;. The &man.mdmfs.8; utility
by default (without <option>-M</option>) creates a swap-based
disk. For more details, please refer to &man.mdconfig.8;
and &man.mdmfs.8; manual pages.</para>
</sect2>
<sect2>
<title>Detaching a Memory Disk from the System</title>
<indexterm>
<primary>disks</primary>
<secondary>detaching a memory disk</secondary>
</indexterm>
<para>When a memory-based or file-based file system
is not used, you should release all resources to the system.
The first thing to do is to unmount the file system, then use
&man.mdconfig.8; to detach the disk from the system and release
the resources.</para>
<para>For example to detach and free all resources used by
<filename>/dev/md4</filename>:</para>
<screen>&prompt.root; <userinput>mdconfig -d -u <replaceable>4</replaceable></userinput></screen>
<para>It is possible to list information about configured
&man.md.4; devices in using the command <command>mdconfig
-l</command>.</para>
<para>For FreeBSD&nbsp;4.X, &man.vnconfig.8; is used to detach
the device. For example to detach and free all resources
used by <filename>/dev/vn4</filename>:</para>
<screen>&prompt.root; <userinput>vnconfig -u vn<replaceable>4</replaceable></userinput></screen>
</sect2> </sect2>
</sect1> </sect1>