docs/53501: [PATCH] Handbook: update snapshots section of disks chapter

Lukas Ertl l.ertl at univie.ac.at
Thu Jun 19 16:00:35 UTC 2003


>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 at 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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