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Editorial review of mirror chapter.

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Mostly fixes to acronyms, links, and "filesystems" and sentences beginning
with commands.

Sponsored by:	iXsystems
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Dru Lavigne 2014-04-25 14:48:46 +00:00
parent 7680bfa8e7
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Notes: svn2git 2020-12-08 03:00:23 +00:00 
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en_US.ISO8859-1/books/handbook/geom/chapter.xml
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@ -295,8 +295,8 @@ Done.</screen>
</warning>
<warning>
<para>&man.dump.8; is used in these procedures to copy file
systems. But &man.dump.8; does not work on file systems with
<para>While <command>dump</command> is used in these procedures to copy file
systems, it does not work on file systems with
soft updates journaling. See &man.tunefs.8; for information
on detecting and disabling soft updates journaling.</para>
</warning>
@ -307,34 +307,34 @@ Done.</screen>
<para>Many disk systems store metadata at the end of each disk.
Old metadata should be erased before reusing the disk for a
mirror. Most problems are caused by two particular types of
leftover metadata: GPT partition tables, and old
&man.gmirror.8; metadata from a previous mirror.</para>
leftover metadata: <acronym>GPT</acronym> partition tables and old
metadata from a previous mirror.</para>
<para>GPT metadata can be erased with &man.gpart.8;. This
example erases both primary and backup GPT partition tables
<para><acronym>GPT</acronym> metadata can be erased with <command>gpart</command>. This
example erases both primary and backup <acronym>GPT</acronym> partition tables
from disk <filename>ada8</filename>:</para>
<screen>&prompt.root; <userinput>gpart destroy -F ada8</userinput></screen>
<para>&man.gmirror.8; can remove a disk from an active mirror
and erase the metadata in one step. Here, the example disk
<para>A disk can be removed from an active mirror and the
metadata erased in one step using <command>gmirror</command>. Here, the example disk
<filename>ada8</filename> is removed from the active
mirror <filename>gm4</filename>:</para>
<screen>&prompt.root; <userinput>gmirror remove gm4 ada8</userinput></screen>
<para>If the mirror is not running but old mirror metadata is
<para>If the mirror is not running, but old mirror metadata is
still on the disk, use <command>gmirror clear</command> to
remove it:</para>
<screen>&prompt.root; <userinput>gmirror clear ada8</userinput></screen>
<para>&man.gmirror.8; stores one block of metadata at the end of
the disk. Because GPT partition schemes also store metadata
at the end of the disk, mirroring entire GPT disks with
&man.gmirror.8; is not recommended. MBR partitioning is used
<para>When <command>gmirror</command> is used, one block of metadata is stored at the end of
the disk. Because <acronym>GPT</acronym> partition schemes also store metadata
at the end of the disk, mirroring entire <acronym>GPT</acronym> disks with
<command>gmirror</command> is not recommended. <acronym>MBR</acronym> partitioning is used
here because it only stores a partition table at the start of
the disk and does not conflict with &man.gmirror.8;.</para>
the disk and does not conflict with <command>gmirror</command>.</para>
</sect2>
<sect2 xml:id="geom-mirror-two-new-disks">
@ -347,8 +347,8 @@ Done.</screen>
system. A new mirror will be created on these two disks and
used to replace the old single disk.</para>
<para>&man.gmirror.8; requires a kernel module,
<filename>geom_mirror.ko</filename>, either built into the
<para>The
<filename>geom_mirror.ko</filename> kernel module must either be built into the
kernel or loaded at boot- or run-time. Manually load the
kernel module now:</para>
@ -358,17 +358,17 @@ Done.</screen>
<screen>&prompt.root; <userinput>gmirror label -v gm0 /dev/ada1 /dev/ada2</userinput></screen>
<para><filename>gm0</filename> is a user-chosen device name
<para>In this example, <filename>gm0</filename> is a user-chosen device name
assigned to the new mirror. After the mirror has been
started, this device name will appear in
<filename>/dev/mirror/</filename>.</para>
<para>MBR and bsdlabel partition tables can now be created on
the mirror with &man.gpart.8;. Here we show a traditional
split-filesystem layout, with partitions for
<para><acronym>MBR</acronym> and <application>bsdlabel</application> partition tables can now be created on
the mirror with <command>gpart</command>. This example uses a traditional
file system layout, with partitions for
<filename>/</filename>, swap, <filename>/var</filename>,
<filename>/tmp</filename>, and <filename>/usr</filename>. A
single <filename>/</filename> filesystem and a swap partition
single <filename>/</filename> file system and a swap partition
will also work.</para>
<para>Partitions on the mirror do not have to be the same size
@ -400,14 +400,14 @@ Done.</screen>
18874370 137426928 6 freebsd-ufs (65G)
156301298 1 - free - (512B)</screen>
<para>Make the mirror bootable by installing bootcode in the MBR
<para>Make the mirror bootable by installing bootcode in the <acronym>MBR</acronym>
and bsdlabel and setting the active slice:</para>
<screen>&prompt.root; <userinput>gpart bootcode -b /boot/mbr mirror/gm0</userinput>
&prompt.root; <userinput>gpart set -a active -i 1 mirror/gm0</userinput>
&prompt.root; <userinput>gpart bootcode -b /boot/boot mirror/gm0s1</userinput></screen>
<para>Format the filesystems on the new mirror, enabling
<para>Format the file systems on the new mirror, enabling
soft-updates.</para>
<screen>&prompt.root; <userinput>newfs -U /dev/mirror/gm0s1a</userinput>
@ -415,9 +415,9 @@ Done.</screen>
&prompt.root; <userinput>newfs -U /dev/mirror/gm0s1e</userinput>
&prompt.root; <userinput>newfs -U /dev/mirror/gm0s1f</userinput></screen>
<para>Filesystems from the original
<para>File systems from the original
<filename>ada0</filename> disk can now be copied onto the
mirror with &man.dump.8; and &man.restore.8;.</para>
mirror with <command>dump</command> and <command>restore</command>.</para>
<screen>&prompt.root; <userinput>mount /dev/mirror/gm0s1a /mnt</userinput>
&prompt.root; <userinput>dump -C16 -b64 -0aL -f - / | (cd /mnt &amp;&amp; restore -rf -)</userinput>
@ -428,8 +428,8 @@ Done.</screen>
&prompt.root; <userinput>dump -C16 -b64 -0aL -f - /tmp | (cd /mnt/tmp &amp;&amp; restore -rf -)</userinput>
&prompt.root; <userinput>dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr &amp;&amp; restore -rf -)</userinput></screen>
<para><filename>/mnt/etc/fstab</filename> must be edited to
point to the new mirror filesystems:</para>
<para>Next, edit <filename>/mnt/etc/fstab</filename> to
point to the new mirror file systems:</para>
<programlisting># Device Mountpoint FStype Options Dump Pass#
/dev/mirror/gm0s1a / ufs rw 1 1
@ -438,21 +438,21 @@ Done.</screen>
/dev/mirror/gm0s1e /tmp ufs rw 2 2
/dev/mirror/gm0s1f /usr ufs rw 2 2</programlisting>
<para>If the &man.gmirror.8; kernel module has not been built
<para>If the <filename>geom_mirror.ko</filename> kernel module has not been built
into the kernel, <filename>/mnt/boot/loader.conf</filename> is
edited to load the module at boot:</para>
<programlisting>geom_mirror_load="YES"</programlisting>
<para>Reboot the system to test the new mirror and verify that
all data has been copied. The BIOS will see the mirror as two
all data has been copied. The <acronym>BIOS</acronym> will see the mirror as two
individual drives rather than a mirror. Because the drives
are identical, it does not matter which is selected to
boot.</para>
<para>See the <link
linkend="gmirror-troubleshooting">Troubleshooting</link>
section if there are problems booting. Powering down and
<para>See <xref
linkend="gmirror-troubleshooting"/>
if there are problems booting. Powering down and
disconnecting the original <filename>ada0</filename> disk
will allow it to be kept as an offline backup.</para>
@ -469,17 +469,17 @@ Done.</screen>
system. A one-disk mirror will be created on the new disk,
the existing system copied onto it, and then the old disk will
be inserted into the mirror. This slightly complex procedure
is required because &man.gmirror.8; needs to put a 512-byte
is required because <command>gmirror</command> needs to put a 512-byte
block of metadata at the end of each disk, and the existing
<filename>ada0</filename> has usually had all of its space
already allocated.</para>
<para>Load the &man.gmirror.8; kernel module:</para>
<para>Load the <filename>geom_mirror.ko</filename> kernel module:</para>
<screen>&prompt.root; <userinput>gmirror load</userinput></screen>
<para>Check the media size of the original disk with
&man.diskinfo.8;:</para>
<command>diskinfo</command>:</para>
<screen>&prompt.root; <userinput>diskinfo -v ada0 | head -n3</userinput>
/dev/ada0
@ -488,39 +488,37 @@ Done.</screen>
<para>Create a mirror on the new disk. To make certain that the
mirror capacity is not any larger than the original drive,
&man.gnop.8; is used to create a fake drive of the exact same
<command>gnop</command> is used to create a fake drive of the exact same
size. This drive does not store any data, but is used only to
limit the size of the mirror. When &man.gmirror.8; creates
limit the size of the mirror. When <command>gmirror</command> creates
the mirror, it will restrict the capacity to the size of
<filename>gzero.nop</filename>, even if the new drive
(<filename>ada1</filename>) has more space. Note that the
<replaceable>1000204821504</replaceable> in the second line
should be equal to <filename>ada0</filename>'s media size
as shown by &man.diskinfo.8; above.</para>
as shown by <command>diskinfo</command> above.</para>
<screen>&prompt.root; <userinput>geom zero load</userinput>
&prompt.root; <userinput>gnop create -s 1000204821504 gzero</userinput>
&prompt.root; <userinput>gmirror label -v gm0 gzero.nop ada1</userinput>
&prompt.root; <userinput>gmirror forget gm0</userinput></screen>
<para><filename>gzero.nop</filename> does not store any
data, so the mirror does not see it as connected. The mirror
<para>Since <filename>gzero.nop</filename> does not store any
data, the mirror does not see it as connected. The mirror
is told to <quote>forget</quote> unconnected components,
removing references to <filename>gzero.nop</filename>.
The result is a mirror device containing only a single disk,
<filename>ada1</filename>.</para>
<para>After creating <filename>gm0</filename>, view the
partition table on <filename>ada0</filename>.</para>
<para>This output is from a 1&nbsp;TB drive. If there is some
partition table on <filename>ada0</filename>. This output is from a 1&nbsp;TB drive. If there is some
unallocated space at the end of the drive, the contents may be
copied directly from <filename>ada0</filename> to the new
mirror.</para>
<para>However, if the output shows that all of the space on the
disk is allocated like the following listing, there is no
space available for the 512-byte &man.gmirror.8; metadata at
disk is allocated, like in the following listing, there is no
space available for the 512-byte mirror metadata at
the end of the disk.</para>
<screen>&prompt.root; <userinput>gpart show ada0</userinput>
@ -533,9 +531,8 @@ Done.</screen>
be explained later.</para>
<para>In either case, partition tables on the primary disk
should be copied first with the &man.gpart.8;
<command>backup</command> and <command>restore</command>
subcommands.</para>
should be first copied using <command>gpart backup</command>
and <command>gpart restore</command>.</para>
<screen>&prompt.root; <userinput>gpart backup ada0 &gt; table.ada0</userinput>
&prompt.root; <userinput>gpart backup ada0s1 &gt; table.ada0s1</userinput></screen>
@ -615,7 +612,7 @@ BSD 8
<para>Both the slice and the last partition should have some
free space at the end of each disk.</para>
<para>Create filesystems on these new partitions. The
<para>Create file systems on these new partitions. The
number of partitions will vary, matching the partitions on the
original disk, <filename>ada0</filename>.</para>
@ -625,7 +622,7 @@ BSD 8
&prompt.root; <userinput>newfs -U /dev/mirror/gm0s1f</userinput>
&prompt.root; <userinput>newfs -U /dev/mirror/gm0s1g</userinput></screen>
<para>Make the mirror bootable by installing bootcode in the MBR
<para>Make the mirror bootable by installing bootcode in the <acronym>MBR</acronym>
and bsdlabel and setting the active slice:</para>
<screen>&prompt.root; <userinput>gpart bootcode -b /boot/mbr mirror/gm0</userinput>
@ -650,15 +647,15 @@ BSD 8
/dev/mirror/gm0s1f /data1 ufs rw 2 2
/dev/mirror/gm0s1g /data2 ufs rw 2 2</programlisting>
<para>If the &man.gmirror.8; kernel module has not been built
<para>If the <filename>geom_mirror.ko</filename> kernel module has not been built
into the kernel, edit <filename>/boot/loader.conf</filename>
to load it:</para>
<programlisting>geom_mirror_load="YES"</programlisting>
<para>Filesystems from the original disk can now be copied onto
the mirror with &man.dump.8; and &man.restore.8;. Note that
it may take some time to create a snapshot for each filesystem
<para>File systems from the original disk can now be copied onto
the mirror with <command>dump</command> and <command>restore</command>. Note that
it may take some time to create a snapshot for each file system
dumped with <command>dump -L</command>.</para>
<screen>&prompt.root; <userinput>mount /dev/mirror/gm0s1a /mnt</userinput>
@ -676,9 +673,9 @@ BSD 8
<filename>ada1</filename>. If everything is working, the
system will boot from <filename>mirror/gm0</filename>,
which now contains the same data as
<filename>ada0</filename> had previously. See the
<link linkend="gmirror-troubleshooting">Troubleshooting</link>
section if there are problems booting.</para>
<filename>ada0</filename> had previously. See
<xref linkend="gmirror-troubleshooting"/>
if there are problems booting.</para>
<para>At this point, the mirror still consists of only the
single <filename>ada1</filename> disk.</para>
@ -694,9 +691,9 @@ BSD 8
<filename>mirror/gm0</filename> has the same contents as
<filename>ada0</filename> before adding
<filename>ada0</filename> to the mirror. If there is
something wrong with the contents copied by &man.dump.8; and
&man.restore.8;, revert <filename>/etc/fstab</filename> to
mount the filesystems on <filename>ada0</filename>,
something wrong with the contents copied by <command>dump</command> and
<command>restore</command>, revert <filename>/etc/fstab</filename> to
mount the file systems on <filename>ada0</filename>,
reboot, and try the whole procedure again.</para>
</important>
@ -704,8 +701,8 @@ BSD 8
GEOM_MIRROR: Device gm0: rebuilding provider ada0</screen>
<para>Synchronization between the two disks will start
immediately. &man.gmirror.8; <command>status</command>
shows the progress.</para>
immediately. Use <command>gmirror status</command>
to view the progress.</para>
<screen>&prompt.root; <userinput>gmirror status</userinput>
Name Status Components
@ -720,7 +717,7 @@ mirror/gm0 DEGRADED ada1 (ACTIVE)
mirror/gm0 COMPLETE ada1 (ACTIVE)
ada0 (ACTIVE)</screen>
<para><filename>mirror/gm0</filename> now consists of
<para>The mirror, <filename>mirror/gm0</filename>, now consists of
the two disks <filename>ada0</filename> and
<filename>ada1</filename>, and the contents are
automatically synchronized with each other. In use,
@ -731,21 +728,12 @@ mirror/gm0 COMPLETE ada1 (ACTIVE)
<sect2 xml:id="gmirror-troubleshooting">
<title>Troubleshooting</title>
<sect3>
<title>Problems with Booting</title>
<sect4>
<title>BIOS Settings</title>
<para>BIOS settings may have to be changed to boot from one
<para>If the system no longer boots, <acronym>BIOS</acronym>
settings may have to be changed to boot from one
of the new mirrored drives. Either mirror drive can be
used for booting, as they contain identical data.</para>
</sect4>
<sect4>
<title>Boot Problems</title>
<para>If the boot stopped with this message, something is
<para>If the boot stops with this message, something is
wrong with the mirror device:</para>
<screen>Mounting from ufs:/dev/mirror/gm0s1a failed with error 19.
@ -771,7 +759,7 @@ Manual root filesystem specification:
mountroot&gt;</screen>
<para>Forgetting to load the
<filename>geom_mirror</filename> module in
<filename>geom_mirror.ko</filename> module in
<filename>/boot/loader.conf</filename> can cause this
problem. To fix it, boot from a &os;&nbsp;9.0 or later
installation media and choose <literal>Shell</literal> at
@ -788,15 +776,15 @@ mountroot&gt;</screen>
<para>Save the file and reboot.</para>
<para>Other problems that cause <literal>error 19</literal>
require more effort to fix. Enter
<literal>ufs:/dev/ada0s1a</literal> at the boot loader
prompt. Although the system should boot from
<para>Other problems that cause <errorname>error 19</errorname>
require more effort to fix. Although the system should boot from
<filename>ada0</filename>, another prompt to select a
shell appears because <filename>/etc/fstab</filename> is
incorrect. Press the Enter key at the prompt. Undo the
modifications so far by reverting
<filename>/etc/fstab</filename>, mounting filesystems from
shell will appear if <filename>/etc/fstab</filename> is
incorrect. Enter
<literal>ufs:/dev/ada0s1a</literal> at the boot loader
prompt and press <keycap>Enter</keycap>. Undo the
edits in
<filename>/etc/fstab</filename> then mount the file systems from
the original disk (<filename>ada0</filename>) instead
of the mirror. Reboot the system and try the procedure
again.</para>
@ -804,8 +792,6 @@ mountroot&gt;</screen>
<screen>Enter full pathname of shell or RETURN for /bin/sh:
&prompt.root; <userinput>cp /etc/fstab.orig /etc/fstab</userinput>
&prompt.root; <userinput>reboot</userinput></screen>
</sect4>
</sect3>
</sect2>
<sect2>
@ -833,9 +819,8 @@ mountroot&gt;</screen>
<screen>&prompt.root; <userinput>gmirror forget gm0</userinput></screen>
<para>Any old metadata should be
<link linkend="geom-mirror-metadata">cleared from the
replacement disk</link>. Then the disk,
<para>Any old metadata should be cleared from the replacement disk using the instructions in
<xref linkend="geom-mirror-metadata"/>. Then the disk,
<filename>ada4</filename> for this example, is inserted into
the mirror:</para>