svn commit: r44699 - head/en_US.ISO8859-1/books/handbook/geom
Dru Lavigne
dru at FreeBSD.org
Tue Apr 29 17:45:18 UTC 2014
Author: dru
Date: Tue Apr 29 17:45:17 2014
New Revision: 44699
URL: http://svnweb.freebsd.org/changeset/doc/44699
Log:
Editorial review of gjournal section.
Sponsored by: iXsystems
Modified:
head/en_US.ISO8859-1/books/handbook/geom/chapter.xml
Modified: head/en_US.ISO8859-1/books/handbook/geom/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/geom/chapter.xml Tue Apr 29 16:59:28 2014 (r44698)
+++ head/en_US.ISO8859-1/books/handbook/geom/chapter.xml Tue Apr 29 17:45:17 2014 (r44699)
@@ -1618,10 +1618,14 @@ ufsid/486b6fc16926168e N/A ad4s1f</
<primary>Journaling</primary>
</indexterm>
- <para>Beginning with &os; 7.0, support for UFS journals is
+ <para>Beginning with &os; 7.0, support for journals on
+ <acronym>UFS</acronym> file systems is
available. The implementation is provided through the
<acronym>GEOM</acronym> subsystem and is configured using
- &man.gjournal.8;.</para>
+ <command>gjournal</command>. Unlike other file system journaling implementations, the
+ <command>gjournal</command> method is block based and not
+ implemented as part of the file system. It is a
+ <acronym>GEOM</acronym> extension.</para>
<para>Journaling stores a log of file system transactions, such as
changes that make up a complete disk write operation, before
@@ -1633,55 +1637,44 @@ ufsid/486b6fc16926168e N/A ad4s1f</
data loss and inconsistencies of the file system. Unlike Soft
Updates, which tracks and enforces meta-data updates, and
snapshots, which create an image of the file system, a log is
- stored in disk space specifically for this task, and in
- some cases, may be stored on another disk entirely.</para>
-
- <para>Unlike other file system journaling implementations, the
- <command>gjournal</command> method is block based and not
- implemented as part of the file system. It is a
- <acronym>GEOM</acronym> extension.</para>
+ stored in disk space specifically for this task. For better
+ performance, the journal may be stored on another
+ disk. In this configuration, the journal provider or storage
+ device should be listed after the device to enable journaling
+ on.</para>
- <para>To enable support for <command>gjournal</command>, the
- &os; kernel must have the following option which is the
- default on &os; 7.0 and later:</para>
-
- <programlisting>options UFS_GJOURNAL</programlisting>
-
- <para>If journaled volumes need to be mounted during startup, the
- <filename>geom_journal.ko</filename> kernel module needs to be
- loaded, by adding the following line to
+ <para>The <filename>GENERIC</filename> kernel provides support
+ for <command>gjournal</command>. To automatically load the
+ <filename>geom_journal.ko</filename> kernel module at boot time,
+ add the following line to
<filename>/boot/loader.conf</filename>:</para>
<programlisting>geom_journal_load="YES"</programlisting>
- <para>Alternatively, this function can be built into a custom
- kernel, by adding the following line in the kernel configuration
+ <para>If a custom
+ kernel is used, ensure the following line is in the kernel configuration
file:</para>
<programlisting>options GEOM_JOURNAL</programlisting>
- <para>Creating a journal on a free file system may now be done
+ <para>Once the module is loaded, a journal can be created on a new
+ file system
using the following steps. In this example,
<filename>da4</filename> is a new <acronym>SCSI</acronym>
disk:</para>
<screen>&prompt.root; <userinput>gjournal load</userinput>
-&prompt.root; <userinput>gjournal label /dev/da4</userinput></screen>
-
- <para>At this point, there should be a
- <filename>/dev/da4</filename> device node and a
- <filename>/dev/da4.journal</filename> device node.
- A file system may now be created on this device:</para>
+&prompt.root; <userinput>gjournal label /dev/<replaceable>da4</replaceable></userinput></screen>
- <screen>&prompt.root; <userinput>newfs -O 2 -J /dev/da4.journal</userinput></screen>
+ <para>This will load the module and create a <filename>/dev/da4.journal</filename>
+ device node on
+ <filename>/dev/da4</filename>.</para>
- <para>This command will create a <acronym>UFS</acronym>2 file
- system on the journaled device.</para>
+ <para>A <acronym>UFS</acronym> file system may now be created on the
+ journaled device, then mounted on an existing mount point:</para>
- <para><command>mount</command> the device at the desired point
- with:</para>
-
- <screen>&prompt.root; <userinput>mount /dev/da4.journal <replaceable>/mnt</replaceable></userinput></screen>
+ <screen>&prompt.root; <userinput>newfs -O 2 -J /dev/<replaceable>da4</replaceable>.journal</userinput>
+&prompt.root; <userinput>mount /dev/<replaceable>da4</replaceable>.journal <replaceable>/mnt</replaceable></userinput></screen>
<note>
<para>In the case of several slices, a journal will be created
@@ -1693,18 +1686,17 @@ ufsid/486b6fc16926168e N/A ad4s1f</
<filename>ad4s2.journal</filename>.</para>
</note>
- <para>For better performance, the journal may be kept on another
- disk. In this configuration, the journal provider or storage
- device should be listed after the device to enable journaling
- on. Journaling may also be enabled on current file systems by
+ <para>Journaling may also be enabled on current file systems by
using <command>tunefs</command>. However,
<emphasis>always</emphasis> make a backup before attempting to
- alter a file system. In most cases, <command>gjournal</command>
+ alter an existing file system. In most cases, <command>gjournal</command>
will fail if it is unable to create the journal, but this does
not protect against data loss incurred as a result of misusing
- <command>tunefs</command>.</para>
+ <command>tunefs</command>. Refer to &man.gjournal.8; and
+ &man.tunefs.8; for more information about these
+ commands.</para>
- <para>It is also possible to journal the boot disk of a &os;
+ <para>It is possible to journal the boot disk of a &os;
system. Refer to the article <link
xlink:href="&url.articles.gjournal-desktop;">Implementing UFS
Journaling on a Desktop PC</link> for detailed
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