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@ -70,79 +70,84 @@
<releaseinfo>$FreeBSD$</releaseinfo> <releaseinfo>$FreeBSD$</releaseinfo>
<abstract> <abstract>
<para>This article covers the use of solid state disk devices in &os; <para>This article covers the use of solid state disk devices in
to create embedded systems.</para> &os; to create embedded systems.</para>
<para>Embedded systems have the advantage of increased stability due to <para>Embedded systems have the advantage of increased stability
the lack of integral moving parts (hard drives). Account must be due to the lack of integral moving parts (hard drives).
taken, however, for the generally low disk space available in the Account must be taken, however, for the generally low disk
system and the durability of the storage medium.</para> space available in the system and the durability of the
storage medium.</para>
<para>Specific topics to be covered include the types and attributes of <para>Specific topics to be covered include the types and
solid state media suitable for disk use in &os;, kernel options attributes of solid state media suitable for disk use in &os;,
that are of interest in such an environment, the kernel options that are of interest in such an environment,
<filename>rc.initdiskless</filename> mechanisms that automate the the <filename>rc.initdiskless</filename> mechanisms that
initialization of such systems and the need for read-only filesystems, automate the initialization of such systems and the need for
and building filesystems from scratch. The article will conclude read-only filesystems, and building filesystems from scratch.
with some general strategies for small and read-only &os; The article will conclude with some general strategies for
environments.</para> small and read-only &os; environments.</para>
</abstract> </abstract>
</articleinfo> </articleinfo>
<sect1 id="intro"> <sect1 id="intro">
<title>Solid State Disk Devices</title> <title>Solid State Disk Devices</title>
<para>The scope of this article will be limited to solid state disk <para>The scope of this article will be limited to solid state
devices made from flash memory. Flash memory is a solid state memory disk devices made from flash memory. Flash memory is a solid
(no moving parts) that is non-volatile (the memory maintains data even state memory (no moving parts) that is non-volatile (the memory
after all power sources have been disconnected). Flash memory can maintains data even after all power sources have been
withstand tremendous physical shock and is reasonably fast (the flash disconnected). Flash memory can withstand tremendous physical
memory solutions covered in this article are slightly slower than a EIDE shock and is reasonably fast (the flash memory solutions covered
hard disk for write operations, and much faster for read operations). in this article are slightly slower than a EIDE hard disk for
One very important aspect of flash memory, the ramifications of which write operations, and much faster for read operations). One
will be discussed later in this article, is that each sector has a very important aspect of flash memory, the ramifications of
limited rewrite capacity. You can only write, erase, and write again to which will be discussed later in this article, is that each
a sector of flash memory a certain number of times before the sector sector has a limited rewrite capacity. You can only write,
becomes permanently unusable. Although many flash memory products erase, and write again to a sector of flash memory a certain
automatically map bad blocks, and although some even distribute write number of times before the sector becomes permanently unusable.
operations evenly throughout the unit, the fact remains that there Although many flash memory products automatically map bad
exists a limit to the amount of writing that can be done to the device. blocks, and although some even distribute write operations
Competitive units have between 1,000,000 and 10,000,000 writes per evenly throughout the unit, the fact remains that there exists a
sector in their specification. This figure varies due to the limit to the amount of writing that can be done to the device.
temperature of the environment.</para> Competitive units have between 1,000,000 and 10,000,000 writes
per sector in their specification. This figure varies due to
the temperature of the environment.</para>
<para>Specifically, we will be discussing ATA compatible compact-flash <para>Specifically, we will be discussing ATA compatible
units, which are quite popular as storage media for digital compact-flash units, which are quite popular as storage media
cameras. Of particular interest is the fact that they pin out directly for digital cameras. Of particular interest is the fact that
to the IDE bus and are compatible with the ATA command set. Therefore, they pin out directly to the IDE bus and are compatible with the
with a very simple and low-cost adaptor, these devices can be attached ATA command set. Therefore, with a very simple and low-cost
directly to an IDE bus in a computer. Once implemented in this manner, adaptor, these devices can be attached directly to an IDE bus in
operating systems such as &os; see the device as a normal hard disk a computer. Once implemented in this manner, operating systems
(albeit small).</para> such as &os; see the device as a normal hard disk (albeit
small).</para>
<para>Other solid state disk solutions do exist, but their expense, <para>Other solid state disk solutions do exist, but their
obscurity, and relative unease of use places them beyond the scope of expense, obscurity, and relative unease of use places them
this article.</para> beyond the scope of this article.</para>
</sect1> </sect1>
<sect1 id="kernel"> <sect1 id="kernel">
<title>Kernel Options</title> <title>Kernel Options</title>
<para>A few kernel options are of specific interest to those creating <para>A few kernel options are of specific interest to those
an embedded &os; system.</para> creating an embedded &os; system.</para>
<para>All embedded &os; systems that use flash memory as system <para>All embedded &os; systems that use flash memory as system
disk will be interested in memory disks and memory filesystems. Because disk will be interested in memory disks and memory filesystems.
of the limited number of writes that can be done to flash memory, the Because of the limited number of writes that can be done to
disk and the filesystems on the disk will most likely be mounted flash memory, the disk and the filesystems on the disk will most
read-only. In this environment, filesystems such as likely be mounted read-only. In this environment, filesystems
<filename>/tmp</filename> and <filename>/var</filename> are mounted as such as <filename>/tmp</filename> and <filename>/var</filename>
memory filesystems to allow the system to create logs and update are mounted as memory filesystems to allow the system to create
counters and temporary files. Memory filesystems are a critical logs and update counters and temporary files. Memory
component to a successful solid state &os; implementation.</para> filesystems are a critical component to a successful solid state
&os; implementation.</para>
<para>You should make sure the following lines exist in your kernel <para>You should make sure the following lines exist in your
configuration file:</para> kernel configuration file:</para>
<programlisting>options MFS # Memory Filesystem <programlisting>options MFS # Memory Filesystem
options MD_ROOT # md device usable as a potential root device options MD_ROOT # md device usable as a potential root device
@ -150,58 +155,63 @@ pseudo-device md # memory disk</programlisting>
</sect1> </sect1>
<sect1 id="ro-fs"> <sect1 id="ro-fs">
<title>The <literal>rc</literal> Subsystem and Read-Only Filesystems</title> <title>The <literal>rc</literal> Subsystem and Read-Only
Filesystems</title>
<para>The post-boot initialization of an embedded &os; system is <para>The post-boot initialization of an embedded &os; system is
controlled by <filename>/etc/rc.initdiskless</filename>.</para> controlled by <filename>/etc/rc.initdiskless</filename>.</para>
<para><filename>/etc/rc.d/var</filename> mounts <filename>/var</filename> <para><filename>/etc/rc.d/var</filename> mounts
as a memory filesystem, makes a configurable list of directories in <filename>/var</filename> as a memory filesystem, makes a
<filename>/var</filename> with the &man.mkdir.1; command, and configurable list of directories in <filename>/var</filename>
changes modes on some of those directories. In the execution of with the &man.mkdir.1; command, and changes modes on some of
those directories. In the execution of
<filename>/etc/rc.d/var</filename>, one other <filename>/etc/rc.d/var</filename>, one other
<filename>rc.conf</filename> variable comes into play &ndash; <filename>rc.conf</filename> variable comes into play &ndash;
<literal>varsize</literal>. The <filename>/etc/rc.d/var</filename> <literal>varsize</literal>. The
file creates a <filename>/var</filename> partition based on the value of <filename>/etc/rc.d/var</filename> file creates a
<filename>/var</filename> partition based on the value of
this variable in <filename>rc.conf</filename>:</para> this variable in <filename>rc.conf</filename>:</para>
<programlisting>varsize=8192</programlisting> <programlisting>varsize=8192</programlisting>
<para>Remember that this value is in sectors by default.</para> <para>Remember that this value is in sectors by default.</para>
<para>The fact that <filename>/var</filename> <para>The fact that <filename>/var</filename> is a read-write
is a read-write filesystem is an important filesystem is an important distinction, as the
distinction, as the <filename>/</filename> partition (and any other <filename>/</filename> partition (and any other partitions you
partitions you may have on your flash media) should be mounted may have on your flash media) should be mounted read-only.
read-only. Remember that in <xref linkend="intro"/> we detailed the Remember that in <xref linkend="intro"/> we detailed the
limitations of flash memory - specifically the limited write capability. limitations of flash memory - specifically the limited write
The importance of not mounting filesystems on flash media read-write, capability. The importance of not mounting filesystems on flash
and the importance of not using a swap file, cannot be overstated. A media read-write, and the importance of not using a swap file,
swap file on a busy system can burn through a piece of flash media in cannot be overstated. A swap file on a busy system can burn
less than one year. Heavy logging or temporary file creation and through a piece of flash media in less than one year. Heavy
destruction can do the same. Therefore, in addition to removing the logging or temporary file creation and destruction can do the
same. Therefore, in addition to removing the
<literal>swap</literal> entry from your <literal>swap</literal> entry from your
<filename>/etc/fstab</filename> file, you should also change the Options <filename>/etc/fstab</filename> file, you should also change the
field for each filesystem to <literal>ro</literal> as follows:</para> Options field for each filesystem to <literal>ro</literal> as
follows:</para>
<programlisting># Device Mountpoint FStype Options Dump Pass# <programlisting># Device Mountpoint FStype Options Dump Pass#
/dev/ad0s1a / ufs ro 1 1</programlisting> /dev/ad0s1a / ufs ro 1 1</programlisting>
<para>A few applications in the average system will immediately begin to <para>A few applications in the average system will immediately
fail as a result of this change. For instance, cron begin to fail as a result of this change. For instance, cron
will not run properly as a result of missing cron tabs in the will not run properly as a result of missing cron tabs in the
<filename>/var</filename> created by <filename>/var</filename> created by
<filename>/etc/rc.d/var</filename>, and syslog and dhcp will <filename>/etc/rc.d/var</filename>, and syslog and dhcp will
encounter problems as well as a result of the read-only filesystem and encounter problems as well as a result of the read-only
missing items in the <filename>/var</filename> that filesystem and missing items in the <filename>/var</filename>
<filename>/etc/rc.d/var</filename> has created. These are only that <filename>/etc/rc.d/var</filename> has created. These are
temporary problems though, and are addressed, along with solutions to only temporary problems though, and are addressed, along with
the execution of other common software packages in solutions to the execution of other common software packages in
<xref linkend="strategies"/>.</para> <xref linkend="strategies"/>.</para>
<para>An important thing to remember is that a filesystem that was mounted <para>An important thing to remember is that a filesystem that was
read-only with <filename>/etc/fstab</filename> can be made read-write at mounted read-only with <filename>/etc/fstab</filename> can be
any time by issuing the command:</para> made read-write at any time by issuing the command:</para>
<screen>&prompt.root; <userinput>/sbin/mount -uw <replaceable>partition</replaceable></userinput></screen> <screen>&prompt.root; <userinput>/sbin/mount -uw <replaceable>partition</replaceable></userinput></screen>
@ -213,73 +223,79 @@ pseudo-device md # memory disk</programlisting>
<sect1> <sect1>
<title>Building a File System From Scratch</title> <title>Building a File System From Scratch</title>
<para>Because ATA compatible compact-flash cards are seen by &os; as <para>Because ATA compatible compact-flash cards are seen by &os;
normal IDE hard drives, you could as normal IDE hard drives, you could theoretically install &os;
theoretically install &os; from the network using the kern and from the network using the kern and mfsroot floppies or from a
mfsroot floppies or from a CD.</para> CD.</para>
<para>However, even a small installation of &os; using normal <para>However, even a small installation of &os; using normal
installation procedures can produce a system in size of greater than 200 installation procedures can produce a system in size of greater
megabytes. Because most people will be using smaller flash memory than 200 megabytes. Because most people will be using smaller
devices (128 megabytes is considered fairly large - 32 or even 16 flash memory devices (128 megabytes is considered fairly large -
megabytes is common) an installation using normal mechanisms is not 32 or even 16 megabytes is common) an installation using normal
possible&mdash;there is simply not enough disk space for even the mechanisms is not possible&mdash;there is simply not enough disk
smallest of conventional installations.</para> space for even the smallest of conventional
installations.</para>
<para>The easiest way to overcome this space limitation is to install <para>The easiest way to overcome this space limitation is to
&os; using conventional means to a normal hard disk. After the install &os; using conventional means to a normal hard disk.
installation is complete, pare down the operating system to a size that After the installation is complete, pare down the operating
will fit onto your flash media, then tar the entire filesystem. The system to a size that will fit onto your flash media, then tar
following steps will guide you through the process of preparing a piece the entire filesystem. The following steps will guide you
of flash memory for your tarred filesystem. Remember, because a normal through the process of preparing a piece of flash memory for
installation is not being performed, operations such as partitioning, your tarred filesystem. Remember, because a normal installation
labeling, file-system creation, etc. need to be performed by hand. In is not being performed, operations such as partitioning,
addition to the kern and mfsroot floppy disks, you will also need to use labeling, file-system creation, etc. need to be performed by
the fixit floppy.</para> hand. In addition to the kern and mfsroot floppy disks, you
will also need to use the fixit floppy.</para>
<procedure> <procedure>
<step> <step>
<title>Partitioning your flash media device</title> <title>Partitioning your flash media device</title>
<para>After booting with the kern and mfsroot floppies, choose <para>After booting with the kern and mfsroot floppies, choose
<literal>custom</literal> from the installation menu. In the custom <literal>custom</literal> from the installation menu. In
installation menu, choose <literal>partition</literal>. In the the custom installation menu, choose
partition menu, you should delete all existing partitions using the <literal>partition</literal>. In the partition menu, you
<keycap>d</keycap> key. After deleting all existing partitions, should delete all existing partitions using the
create a partition using the <keycap>c</keycap> key and accept the <keycap>d</keycap> key. After deleting all existing
default value for the size of the partition. When asked for the partitions, create a partition using the <keycap>c</keycap>
type of the partition, make sure the value is set to key and accept the default value for the size of the
<literal>165</literal>. Now write this partition table to the disk partition. When asked for the type of the partition, make
by pressing the <keycap>w</keycap> key (this is a hidden option on sure the value is set to <literal>165</literal>. Now write
this screen). If you are using an ATA compatible compact this partition table to the disk by pressing the
flash card, you should choose the &os; Boot Manager. Now press <keycap>w</keycap> key (this is a hidden option on this
the <keycap>q</keycap> key to quit the partition menu. You will be screen). If you are using an ATA compatible compact flash
shown the boot manager menu once more - repeat the choice you made card, you should choose the &os; Boot Manager. Now press
earlier.</para> the <keycap>q</keycap> key to quit the partition menu. You
will be shown the boot manager menu once more - repeat the
choice you made earlier.</para>
</step> </step>
<step> <step>
<title>Creating filesystems on your flash memory device</title> <title>Creating filesystems on your flash memory
device</title>
<para>Exit the custom installation menu, and from the main <para>Exit the custom installation menu, and from the main
installation menu choose the <literal>fixit</literal> option. After installation menu choose the <literal>fixit</literal>
entering the fixit environment, enter the following command:</para> option. After entering the fixit environment, enter the
following command:</para>
<screen>&prompt.root; <userinput>disklabel -e /dev/ad0c</userinput></screen> <screen>&prompt.root; <userinput>disklabel -e /dev/ad0c</userinput></screen>
<para>At this point you will have entered the vi editor under the <para>At this point you will have entered the vi editor under
auspices of the disklabel command. Next, you need to add the auspices of the disklabel command. Next, you need to
an <literal>a:</literal> line at the end of the file. This add an <literal>a:</literal> line at the end of the file.
<literal>a:</literal> line should look like:</para> This <literal>a:</literal> line should look like:</para>
<programlisting>a: <replaceable>123456</replaceable> 0 4.2BSD 0 0</programlisting> <programlisting>a: <replaceable>123456</replaceable> 0 4.2BSD 0 0</programlisting>
<para>Where <replaceable>123456</replaceable> is a number that is <para>Where <replaceable>123456</replaceable> is a number that
exactly the same as the number in the existing <literal>c:</literal> is exactly the same as the number in the existing
entry for size. Basically you are duplicating the existing <literal>c:</literal> entry for size. Basically you are
<literal>c:</literal> line as an <literal>a:</literal> line, making duplicating the existing <literal>c:</literal> line as an
sure that fstype is <literal>4.2BSD</literal>. Save the file and <literal>a:</literal> line, making sure that fstype is
exit.</para> <literal>4.2BSD</literal>. Save the file and exit.</para>
<screen>&prompt.root; <userinput>disklabel -B -r /dev/ad0c</userinput> <screen>&prompt.root; <userinput>disklabel -B -r /dev/ad0c</userinput>
&prompt.root; <userinput>newfs /dev/ad0a</userinput></screen> &prompt.root; <userinput>newfs /dev/ad0a</userinput></screen>
@ -292,22 +308,24 @@ pseudo-device md # memory disk</programlisting>
<screen>&prompt.root; <userinput>mount /dev/ad0a /flash</userinput></screen> <screen>&prompt.root; <userinput>mount /dev/ad0a /flash</userinput></screen>
<para>Bring this machine up on the network so we may transfer our tar <para>Bring this machine up on the network so we may transfer
file and explode it onto our flash media filesystem. One example of our tar file and explode it onto our flash media filesystem.
how to do this is:</para> One example of how to do this is:</para>
<screen>&prompt.root; <userinput>ifconfig xl0 192.168.0.10 netmask 255.255.255.0</userinput> <screen>&prompt.root; <userinput>ifconfig xl0 192.168.0.10 netmask 255.255.255.0</userinput>
&prompt.root; <userinput>route add default 192.168.0.1</userinput></screen> &prompt.root; <userinput>route add default 192.168.0.1</userinput></screen>
<para>Now that the machine is on the network, transfer your tar file. <para>Now that the machine is on the network, transfer your
You may be faced with a bit of a dilemma at this point - if your tar file. You may be faced with a bit of a dilemma at this
flash memory part is 128 megabytes, for instance, and your tar file point - if your flash memory part is 128 megabytes, for
is larger than 64 megabytes, you cannot have your tar file on the instance, and your tar file is larger than 64 megabytes, you
flash media at the same time as you explode it - you will run out of cannot have your tar file on the flash media at the same
space. One solution to this problem, if you are using FTP, is to time as you explode it - you will run out of
untar the file while it is transferred over FTP. If you perform space. One solution to this problem, if you are using FTP,
your transfer in this manner, you will never have the tar file and is to untar the file while it is transferred over FTP. If
the tar contents on your disk at the same time:</para> you perform your transfer in this manner, you will never
have the tar file and the tar contents on your disk at the
same time:</para>
<screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| tar xvf -"</userinput></screen> <screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| tar xvf -"</userinput></screen>
@ -316,70 +334,74 @@ pseudo-device md # memory disk</programlisting>
<screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| zcat | tar xvf -"</userinput></screen> <screen><prompt>ftp></prompt> <userinput>get tarfile.tar "| zcat | tar xvf -"</userinput></screen>
<para>After the contents of your tarred filesystem are on your flash <para>After the contents of your tarred filesystem are on your
memory filesystem, you can unmount the flash memory and flash memory filesystem, you can unmount the flash memory
reboot:</para> and reboot:</para>
<screen>&prompt.root; <userinput>cd /</userinput> <screen>&prompt.root; <userinput>cd /</userinput>
&prompt.root; <userinput>umount /flash</userinput> &prompt.root; <userinput>umount /flash</userinput>
&prompt.root; <userinput>exit</userinput></screen> &prompt.root; <userinput>exit</userinput></screen>
<para>Assuming that you configured your filesystem correctly when it <para>Assuming that you configured your filesystem correctly
was built on the normal hard disk (with your filesystems mounted when it was built on the normal hard disk (with your
read-only, and with the necessary options compiled into the kernel) filesystems mounted read-only, and with the necessary
you should now be successfully booting your &os; embedded options compiled into the kernel) you should now be
system.</para> successfully booting your &os; embedded system.</para>
</step> </step>
</procedure> </procedure>
</sect1> </sect1>
<sect1 id="strategies"> <sect1 id="strategies">
<title>System Strategies for Small and Read Only Environments</title> <title>System Strategies for Small and Read Only
Environments</title>
<para>In <xref linkend="ro-fs"/>, it was pointed out that the <para>In <xref linkend="ro-fs"/>, it was pointed out that the
<filename>/var</filename> filesystem constructed by <filename>/var</filename> filesystem constructed by
<filename>/etc/rc.d/var</filename> and the presence of a read-only <filename>/etc/rc.d/var</filename> and the presence of a
root filesystem causes problems with many common software packages used read-only root filesystem causes problems with many common
with &os;. In this article, suggestions for successfully running software packages used with &os;. In this article, suggestions
cron, syslog, ports installations, and the Apache web server will be for successfully running cron, syslog, ports installations, and
provided.</para> the Apache web server will be provided.</para>
<sect2> <sect2>
<title>cron</title> <title>cron</title>
<para>Upon boot, <filename class="directory">/var</filename> gets <para>Upon boot, <filename class="directory">/var</filename>
populated by <filename>/etc/rc.d/var</filename> using the list from gets populated by <filename>/etc/rc.d/var</filename> using the
<filename>/etc/mtree/BSD.var.dist</filename>, so the <filename list from <filename>/etc/mtree/BSD.var.dist</filename>, so the
class="directory">cron</filename>, <filename <filename class="directory">cron</filename>, <filename
class="directory">cron/tabs</filename>, <filename class="directory">cron/tabs</filename>, <filename
class="directory">at</filename>, and a few other standard class="directory">at</filename>, and a few other standard
directories get created.</para> directories get created.</para>
<para>However, this does not solve the problem of maintaining cron <para>However, this does not solve the problem of maintaining
tabs across reboots. When the system reboots, the cron tabs across reboots. When the system reboots, the
<filename>/var</filename> filesystem that is in memory will disappear <filename>/var</filename> filesystem that is in memory will
and any cron tabs you may have had in it will also disappear. disappear and any cron tabs you may have had in it will also
Therefore, one solution would be to create cron tabs for the users disappear. Therefore, one solution would be to create cron
that need them, mount your <filename>/</filename> filesystem as tabs for the users that need them, mount your
read-write and copy those cron tabs to somewhere safe, like <filename>/</filename> filesystem as read-write and copy those
cron tabs to somewhere safe, like
<filename>/etc/tabs</filename>, then add a line to the end of <filename>/etc/tabs</filename>, then add a line to the end of
<filename>/etc/rc.initdiskless</filename> that copies those crontabs into <filename>/etc/rc.initdiskless</filename> that copies those
<filename>/var/cron/tabs</filename> after that directory has been crontabs into <filename>/var/cron/tabs</filename> after that
created during system initialization. You may also need to add a line directory has been created during system initialization. You
that changes modes and permissions on the directories you create and may also need to add a line that changes modes and permissions
the files you copy with <filename>/etc/rc.initdiskless</filename>.</para> on the directories you create and the files you copy with
<filename>/etc/rc.initdiskless</filename>.</para>
</sect2> </sect2>
<sect2> <sect2>
<title>syslog</title> <title>syslog</title>
<para><filename>syslog.conf</filename> specifies the locations of <para><filename>syslog.conf</filename> specifies the locations
certain log files that exist in <filename>/var/log</filename>. These of certain log files that exist in
files are not created by <filename>/etc/rc.d/var</filename> upon <filename>/var/log</filename>. These files are not created by
system initialization. Therefore, somewhere in <filename>/etc/rc.d/var</filename> upon system initialization.
<filename>/etc/rc.d/var</filename>, after the section that creates Therefore, somewhere in <filename>/etc/rc.d/var</filename>,
the directories in <filename>/var</filename>, you will need to add after the section that creates the directories in
something like this:</para> <filename>/var</filename>, you will need to add something like
this:</para>
<screen>&prompt.root; <userinput>touch /var/log/security /var/log/maillog /var/log/cron /var/log/messages</userinput> <screen>&prompt.root; <userinput>touch /var/log/security /var/log/maillog /var/log/cron /var/log/messages</userinput>
&prompt.root; <userinput>chmod 0644 /var/log/*</userinput></screen> &prompt.root; <userinput>chmod 0644 /var/log/*</userinput></screen>
@ -388,27 +410,30 @@ pseudo-device md # memory disk</programlisting>
<sect2> <sect2>
<title>Ports Installation</title> <title>Ports Installation</title>
<para>Before discussing the changes necessary to successfully use the <para>Before discussing the changes necessary to successfully
ports tree, a reminder is necessary regarding the read-only nature of use the ports tree, a reminder is necessary regarding the
your filesystems on the flash media. Since they are read-only, you read-only nature of your filesystems on the flash media.
will need to temporarily mount them read-write using the mount syntax Since they are read-only, you will need to temporarily mount
shown in <xref linkend="ro-fs"/>. You should always remount those them read-write using the mount syntax shown in <xref
linkend="ro-fs"/>. You should always remount those
filesystems read-only when you are done with any maintenance - filesystems read-only when you are done with any maintenance -
unnecessary writes to the flash media could considerably shorten its unnecessary writes to the flash media could considerably
lifespan.</para> shorten its lifespan.</para>
<para>To make it possible to enter a ports directory and successfully <para>To make it possible to enter a ports directory and
run <command>make</command> <maketarget>install</maketarget>, successfully run
we must create a packages directory on <command>make</command> <maketarget>install</maketarget>, we
a non-memory filesystem that will keep track of our packages across must create a packages directory on a non-memory filesystem
reboots. Because it is necessary to mount your filesystems as that will keep track of our packages across reboots. Because
read-write for the installation of a package anyway, it is sensible to it is necessary to mount your filesystems as read-write for
assume that an area on the flash media can also be used for package the installation of a package anyway, it is sensible to assume
that an area on the flash media can also be used for package
information to be written to.</para> information to be written to.</para>
<para>First, create a package database directory. This is normally in <para>First, create a package database directory. This is
<filename>/var/db/pkg</filename>, but we cannot place it there as it normally in <filename>/var/db/pkg</filename>, but we cannot
will disappear every time the system is booted.</para> place it there as it will disappear every time the system is
booted.</para>
<screen>&prompt.root; <userinput>mkdir /etc/pkg</userinput></screen> <screen>&prompt.root; <userinput>mkdir /etc/pkg</userinput></screen>
@ -418,12 +443,13 @@ pseudo-device md # memory disk</programlisting>
<screen>&prompt.root; <userinput>ln -s /etc/pkg /var/db/pkg</userinput></screen> <screen>&prompt.root; <userinput>ln -s /etc/pkg /var/db/pkg</userinput></screen>
<para>Now, any time that you mount your filesystems as read-write and <para>Now, any time that you mount your filesystems as
install a package, the <command>make</command> <maketarget>install</maketarget> will work, read-write and install a package, the
and package information <command>make</command> <maketarget>install</maketarget> will
will be written successfully to <filename>/etc/pkg</filename> (because work, and package information will be written successfully to
the filesystem will, at that time, be mounted read-write) which will <filename>/etc/pkg</filename> (because the filesystem will, at
always be available to the operating system as that time, be mounted read-write) which will always be
available to the operating system as
<filename>/var/db/pkg</filename>.</para> <filename>/var/db/pkg</filename>.</para>
</sect2> </sect2>
@ -431,40 +457,42 @@ pseudo-device md # memory disk</programlisting>
<title>Apache Web Server</title> <title>Apache Web Server</title>
<note> <note>
<para>The steps in this section are only necessary if Apache is <para>The steps in this section are only necessary if Apache
set up to write its pid or log information outside of is set up to write its pid or log information outside of
<filename class="directory">/var</filename>. By default, <filename class="directory">/var</filename>. By default,
Apache keeps its pid file in <filename Apache keeps its pid file in <filename
class="directory">/var/run/httpd.pid</filename> and its log class="directory">/var/run/httpd.pid</filename> and its
files in <filename class="directory">/var/log</filename>.</para> log files in <filename
class="directory">/var/log</filename>.</para>
</note> </note>
<para>It is now assumed that Apache keeps its log files in a <para>It is now assumed that Apache keeps its log files in a
directory <filename directory <filename
class="directory"><replaceable>apache_log_dir</replaceable></filename> class="directory"><replaceable>apache_log_dir</replaceable></filename>
outside of <filename class="directory">/var</filename>. outside of <filename class="directory">/var</filename>.
When this directory lives on a read-only filesystem, Apache will When this directory lives on a read-only filesystem, Apache
not be able to save any log files, and may have problems working. will not be able to save any log files, and may have problems
If so, it is necessary to add a new directory to the working. If so, it is necessary to add a new directory to the
list of directories in <filename>/etc/rc.d/var</filename> to list of directories in <filename>/etc/rc.d/var</filename> to
create in <filename>/var</filename>, and to link create in <filename>/var</filename>, and to link
<filename class="directory"><replaceable>apache_log_dir</replaceable></filename> to <filename
<filename>/var/log/apache</filename>. It is also necessary to set class="directory"><replaceable>apache_log_dir</replaceable></filename>
permissions and ownership on this new directory.</para> to <filename>/var/log/apache</filename>. It is also necessary
to set permissions and ownership on this new directory.</para>
<para>First, add the directory <literal>log/apache</literal> to the list <para>First, add the directory <literal>log/apache</literal> to
of directories to be created in the list of directories to be created in
<filename>/etc/rc.d/var</filename>.</para> <filename>/etc/rc.d/var</filename>.</para>
<para>Second, add these commands to <para>Second, add these commands to
<filename>/etc/rc.d/var</filename> after the directory creation <filename>/etc/rc.d/var</filename> after the directory
section:</para> creation section:</para>
<screen>&prompt.root; <userinput>chmod 0774 /var/log/apache</userinput> <screen>&prompt.root; <userinput>chmod 0774 /var/log/apache</userinput>
&prompt.root; <userinput>chown nobody:nobody /var/log/apache</userinput></screen> &prompt.root; <userinput>chown nobody:nobody /var/log/apache</userinput></screen>
<para>Finally, remove the existing <para>Finally, remove the existing <filename
<filename class="directory"><replaceable>apache_log_dir</replaceable></filename> class="directory"><replaceable>apache_log_dir</replaceable></filename>
directory, and replace it with a link:</para> directory, and replace it with a link:</para>
<screen>&prompt.root; <userinput>rm -rf <filename class="directory"><replaceable>apache_log_dir</replaceable></filename></userinput> <screen>&prompt.root; <userinput>rm -rf <filename class="directory"><replaceable>apache_log_dir</replaceable></filename></userinput>