Date: Tue, 29 Apr 2014 17:45:17 +0000 (UTC) From: Dru Lavigne <dru@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r44699 - head/en_US.ISO8859-1/books/handbook/geom Message-ID: <201404291745.s3THjHUL055269@svn.freebsd.org>
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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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