Date: Thu, 19 Jun 2003 17:50:46 +0200 (CEST) From: Lukas Ertl <l.ertl@univie.ac.at> To: FreeBSD-gnats-submit@FreeBSD.org Subject: docs/53501: [PATCH] Handbook: update snapshots section of disks chapter Message-ID: <200306191550.h5JFoklE081508@korben.in.tern> Resent-Message-ID: <200306191600.h5JG0VfP088130@freefall.freebsd.org>
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>Number: 53501
>Category: docs
>Synopsis: [PATCH] Handbook: update snapshots section of disks chapter
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: doc-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Jun 19 09:00:31 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator: Lukas Ertl
>Release: FreeBSD 5.1-CURRENT i386
>Organization:
Vienna University Computer Center
>Environment:
System: FreeBSD korben 5.1-CURRENT FreeBSD 5.1-CURRENT #14: Wed Jun 18 20:24:25 CEST 2003 le@korben:/usr/obj/usr/src/sys/KORBEN i386
>Description:
>How-To-Repeat:
>Fix:
This patch removes some redundancies and adds a remark of mksnap_ffs(8).
--- disks.diff begins here ---
Index: disks/chapter.sgml
===================================================================
RCS file: /usr/local/bsdcvs/doc/en_US.ISO8859-1/books/handbook/disks/chapter.sgml,v
retrieving revision 1.177
diff -u -r1.177 chapter.sgml
--- disks/chapter.sgml 15 Jun 2003 09:53:45 -0000 1.177
+++ disks/chapter.sgml 19 Jun 2003 15:46:24 -0000
@@ -2524,38 +2524,45 @@
<link linkend="soft-updates">Soft Updates</link>: File system snapshots.</para>
<para>Snapshots allow a user to create images of specified file
- systems, and treat them as a file.
- Snapshot files must be created in the file system that the
- action is performed on, and a user may create no more than 20
- snapshots per file system. Active snapshots are recorded
- in the superblock so they are persistent across unmount and
- remount operations along with system reboots. When a snapshot
- is no longer required, it can be removed with the standard &man.rm.1;
- command. Snapshots may be removed in any order,
- however all the used space may not be acquired because another snapshot will
+ systems, and treat them as a file. Snapshot files must be
+ created in the file system that the action is performed on,
+ and a user may create no more than 20 snapshots per file
+ system. Active snapshots are recorded in the superblock so
+ they are persistent across unmount and remount operations
+ along with system reboots. When a snapshot is no longer
+ required, it can be removed with standard &man.rm.1;.
+ Snapshots may be removed in any order, however all the used
+ space may not be acquired because another snapshot will
possibly claim some of the released blocks.</para>
- <para>During initial creation, the <option>schg</option> flag (see the &man.chflags.1; manual page)
- is set to ensure that even <username>root</username> cannot write to the snapshot.
- The &man.unlink.1; command makes an exception for snapshot files
- since it allows them to be removed
- with the <option>schg</option> flag set, so it is not necessary to
- clear the <option>schg</option> flag before removing a snapshot file.</para>
+ <para>During initial creation, the <option>schg</option> flag
+ (see &man.chflags.1;) is set to ensure that even
+ <username>root</username> cannot write to the snapshot.
+ &man.unlink.1; makes an exception for snapshot files since it
+ allows them to be removed with the <option>schg</option> flag
+ set, so it is not necessary to clear the <option>schg</option>
+ flag before removing a snapshot file.</para>
- <para>Snapshots are created with the &man.mount.8; command. To place
+ <para>Snapshots are created with &man.mount.8;. To place
a snapshot of <filename>/var</filename> in the file
<filename>/var/snapshot/snap</filename> use the following
command:</para>
<screen>&prompt.root; <userinput>mount -u -o snapshot /var/snapshot/snap /var</userinput></screen>
- <para>Once a snapshot has been created, they have several
+ <para>Alternatively, you can use &man.mksnap.ffs.8; to create
+ the snapshot:</para>
+
+<screen>&prompt.root; <userinput>mksnap_ffs /var /var/snapshot/snap</userinput></screen>
+
+ <para>Once a snapshot has been created, it has several
uses:</para>
<itemizedlist>
<listitem>
- <para>Some administrators will use a snapshot file for backup purposes,
- because the snapshot can be transfered to CDs or tape.</para>
+ <para>Some administrators will use a snapshot file for
+ backup purposes, because the snapshot can be transfered to
+ CDs or tape.</para>
</listitem>
<listitem>
@@ -2576,8 +2583,8 @@
</listitem>
<listitem>
- <para>&man.mount.8; the snapshot as a frozen image of the file system.
- To &man.mount.8; the snapshot
+ <para>Mount the snapshot as a frozen image of the file
+ system. To mount the snapshot
<filename>/var/snapshot/snap</filename> run:</para>
<screen>&prompt.root; <userinput>mdconfig -a -t vnode -f /var/snapshot/snap -u 4</userinput></screen>
@@ -2586,20 +2593,21 @@
</listitem>
</itemizedlist>
- <para>You can now walk the hierarchy of your frozen <filename>/var</filename>
- file system mounted at <filename>/mnt</filename>. Everything will
- be in the same state it was during the snapshot creation time.
- The only exception is that any earlier snapshots will appear
- as zero length files. When the use of a snapshot has delimited,
- it can be unmounted with:</para>
+ <para>You can now walk the hierarchy of your frozen
+ <filename>/var</filename> file system mounted at
+ <filename>/mnt</filename>. Everything will be in the same
+ state it was during the snapshot creation time. The only
+ exception is that any earlier snapshots will appear as zero
+ length files. When the use of a snapshot has delimited, it
+ can be unmounted with:</para>
<screen>&prompt.root; <userinput>umount /mnt</userinput></screen>
<screen>&prompt.root; <userinput>mdconfig -d -u 4</userinput></screen>
- <para>For more information about <option>softupdates</option> and
- file system snapshots, including technical papers, you can visit
- Marshall Kirk McKusick's website at
- <ulink url="http://www.mckusick.com/">http://www.mckusick.com.</ulink></para>;
+ <para>For more information about <option>softupdates</option>
+ and file system snapshots, including technical papers, you can
+ visit Marshall Kirk McKusick's website at <ulink
+ url="http://www.mckusick.com/">http://www.mckusick.com.</ulink></para>;
</sect1>
<sect1 id="quotas">
--- disks.diff ends here ---
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>Audit-Trail:
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