Changes between Version 1 and Version 2 of CustomerExperience

Timestamp:

Jan 23, 2007, 5:49:02 PM (18 years ago)

Author:

Bill R. Williams

Comment:

--

CustomerExperience

@@ -1 +1 @@
 == Customer Experience and Feedbacks With Mondorescue ==
+
+== {{{mondoarchive}}} on Red Hat/EL running BIND ({{{/proc}}} also mounted in chroot) ==
+
+This is just a TIP from my observations on:[[BR]]
+Red Hat/EL AS v4.4 running bind-9.2.4-16.EL4[[BR]]
+It may hold true for other versions of Red Hat as well as Fedora.
+
+The {{{named}}} (bind) runs in a ''chroot'' environment, and as part of its
+startup script there is a:
+{{{
+        mount --bind /proc /var/named/chroot/proc
+}}}
+which means (as described in man mount):
+{{{
+       Since Linux 2.4.0 it is possible to remount part of the file
+       hierarchy somewhere else. The call is
+              mount --bind olddir newdir
+       After this call the same contents is accessible in two places.
+}}}
+As a result you have this (edited from {{{df -ha}}}):
+{{{
+Filesystem            Size  Used Avail Use% Mounted on
+...[snip]...
+none                     0     0     0   -  /proc
+...[snip]...
+/proc                    0     0     0   -  /var/named/chroot/proc
+...[snip]...
+}}}
+
+Yes, {{{/proc}}} is mounted in two places, and there's no announcement to
+that effect -- it is not immediately obvious!  You gotta look for it.
+And that extra mount is not automatically excluded by {{{mondoarchive}}}.
+
+What this means is that if you {{{mondoarchive}}} the system without
+excluding that chroot area ({{{/var/named/chroot/proc}}}) you will be
+including it ({{{/proc}}}) in your backup.
+[[BR]]
+(Or you could stop named and: {{{umount /var/named/chroot/proc}}}.)
+
+In any case, the further gotcha is that if you get the
+{{{/var/named/chroot/proc}}} in the backup, it's going to be created when
+you boot/run {{{mondorestore}}}.
+If you booted the {{{mondorestore}}} (CD/DVD) for a system
+recovery, you need to keep in mind:
+ * the {{{named}}} will not be running; therefore, 
+ * the startup script ({{{/etc/init.d/named}}}) will ''not'' have done the "{{{mount --bind /proc /var/named/chroot/proc}}}", which means 
+ * you will create that whole filesystem as ''real'' files/directories in {{{/var/named/chroot/proc}}}.  
+[[BR]]
+Of course, when the
+{{{named}}} startup script is run it should go ahead and do the
+"{{{mount --bind}}}"
+over the top of the junk, but stuff like that just makes me
+nervous.
+
+''ANYWAY'', I just thought I'd drop this observation out there for
+whomever might be interested.
+
+I suspect that such a thing might be the case on other stuff that runs
+in chroot jail.  Maybe it is also true for other non-RH distributions,
+too?
+
+Just something to be aware of.
+[[BR]]
+The moral is:
+''Check your mounts before you do your backup!''
+