Re: [Xen-users] Block level domU backup

["Agent Rooker" <agentrooker@xxxxxxxxx>]

On Fri, Oct 31, 2008 at 9:05 AM, Javier Guerra <javier@xxxxxxxxxxx> wrote:
> On Fri, Oct 31, 2008 at 7:59 AM, Dustin Henning
> <Dustin.Henning@xxxxxxxxxxx> wrote:
>>        You are correct, outgoing packets that were part of a stream would
>> be discarded for being out of order.  However, new connections (for mail
>> about to be delivered from queue, for example) would be established as new
>> connections and go through.  This would be true even if you tried restoring
>> without networking, which may or may not be an option, as the mail would
>> still be in queue upon starting up.
>
> this would also happen with a traditional backup.
>
> not something to lose sleep on
>
>
> --
> Javier
>

Anyway, I finally got around to testing it.  Everything seems to work
just fine.  Here is my script's logfile for the test run with time
stamps.

Oct 31 15:27:20 --> Beginning sync.
Oct 31 15:27:20 --> Pausing domU webserver and saving xen checkpoint file...
Oct 31 15:27:40 --> Creating root snapshot...
  Logical volume "webserver_snapshot" created
Oct 31 15:27:43 --> Creating swap snapshot...
  Logical volume "webserver_swap_snapshot" created
Oct 31 15:27:43 --> Restoring Xen domU...
Oct 31 15:28:03 --> Syncing swap volume...
Oct 31 15:28:29 --> Removing swap snapshot...
  Logical volume "webserver_swap_snapshot" successfully removed
Oct 31 15:28:30 --> Syncing root volume...
Oct 31 15:30:08 --> Removing root snapshot...
  Logical volume "webserver_snapshot" successfully removed
Oct 31 15:30:09 --> Transferring checkpoint file...
Oct 31 15:30:42 --> Transferring config file...
Oct 31 15:30:43 --> Done!

As you can see, the domU remains paused for a little over 40 seconds,
and the snapshots exist for a little more than 2 minutes.  For those 2
minutes, I/O efficiency will suffer, but as long as we do this during
non-peak hours, it should be a non-issue.  I'm still nervous about
some bug in xen causing the domU to not restore after the snapshots
get created, but after some more extensive testing I hope to put that
worry to rest.

I did run into an issue when I restored the domU on the backup server.
 I was not able to ssh in.  That was the only service running on that
domU.  However, after restarting, I was able to ssh just fine, and
everything else seems normal.  I'll keep testing and report any
findings.


-- 
Agent Rooker

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users