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Re: [Xen-users] Backup domU xen

To: Marc Patino Gómez <mpatino@xxxxxxxxxxxx>
Subject: Re: [Xen-users] Backup domU xen
From: Pascal Nobus <pascal@xxxxxxxx>
Date: Thu, 31 Jan 2008 13:42:10 +0100
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It worked for 1 domU, but when doing this with another domU, it resulted in a not responding system because of the load.
Memory is not the problem (dom0 has 746 MB).
This night I made a perfect backup by putting rsyncd.daemon on the domU's, and rsyncing over ethernet to dom0.
There is nothing in the logs (messages,syslog,xend), not a single line.

The problem is within the snapshot I think, it gives me a instant load, but not all the times (about 50% is done without a load-peak)

This is done within 2-seconds:
@xen1:~# cat /proc/loadavg
0.02 0.02 0.00 1/72 8252
@xen1:~# /sbin/lvcreate -L12G -s -n arrowsnapshot /dev/xen-vol/arrow-disk
  Logical volume "arrowsnapshot" created
@xen1:~# cat /proc/loadavg
0.33 0.08 0.03 1/71 8306

Althoug the .33 isn't a problem, the load when crashed was more than 4 (maximum of mrtg-measurement)



Marc Patino Gómez schreef:
Hi,

I used these steps to backup my domUs and never I had this problem.


Pascal Nobus wrote:
.... seem to be a never ending story ...
I've found the problem of my crashes (two days on a row now).

I'm using lvm2 as a filesystem, and was doing backup's like this:
- take a snapshot of a running system
- mount the snapshot
- rsync the snapshot to my backup-partition.
- umount the snapshot
- remove the snaphost
Have your dom0 enough memory? Snapshots requires some aditional memory, so if you had your dom0 limited to 256MB of RAM it could be a problem.

To prevent a not responding system you can use "renice" command to schedule rsync command with low priority.

If you can post more info, like log output of the crash , probably someone in the list could help you.

Regards,

Marc

This resulted in a huge load, which was increased 1 hour later, and resulted in a not-responding system.


I googled now for 2 days, and found many discussions, but I cannot find a proper and stable solution. Should I maybe just mount the domU over the network (portmap) to have a non-crashing solution?

Best regards,
Pascal


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