Re: [Xen-users] Backup DomU volumes

[Marc Patino Gómez <mpatino@xxxxxxxxxxxx>]

Hi Pavel,

Please read LVM Howto for understanding howto LVM snapshots works

http://tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html

making a snapshot is quite easy & quickly, making the backup (rsync, 
tar, bacula,....) isn't quickly :( and its the most horrible part in the 
sysadmin life...

Regards,

Marc




Pavel Georgiev wrote:
> Sounds about right, except that it will probably take too much time to make 
> snapshots of 270GB volumes. How long would that take and how much space would 
> it require.
>
> On Tuesday 02 October 2007 16:57:26 Marc Patino Gómez wrote:
>   
> > Hi Pavel,
> >
> > In my opinion, using LVM will help you. When you want  backup a running
> > VM which his VBD is on a LVM volume you can make a snapshot, then mount
> > the snapshot, after this, make the rsync and finally remove the snapshot.
> >
> > Best regards,
> >
> > Marc
> >
> > Pavel Georgiev wrote:
> >     
> > > Hi List,
> > >
> > > I`m trying backup the volumes of VMs running on a xen server (3.1). I`ll
> > > backup ext3 and reiserfs volumes. My goal is to backup them from Dom0 so
> > > that I can avoid messing with DomU (adding scripts, cronjobs etc.). I
> > > have another server running xen and I plan to keep exactly the same
> > > volumes on it so I can start the VMs on this server in case my main
> > > server dies.
> > >
> > > The way I see it, I`ll be mounting volumes on both servers and
> > > doing 'rsync -avP' on the content (in order to avoid transferring already
> > > existing file). The problem (maybe not a problem of xen, but I guess
> > > other people have bumped into this) is how do I mount volumes without
> > > stopping the VMs and without corrupting the data on the volumes.
> > >
> > > When a volume is in use by a VM, it either has the "need_recovery" flag
> > > (ext3) or cannot be mounted ro (reiserfs). I could remove the
> > > "need_recovery" flag for ext3 volumes and mount them read-only, do the
> > > sync and then umount and set the flag again. For reiserfs I could mount
> > > the volume read-write, remount read-only and then do the sync. Are those
> > > two approaches safe? Is this going to corrupt my volumes, after all I`ll
> > > do some writing (removing the flag for ext3 and replaying the journal for
> > > reiserfs)?
> > >
> > > In general, what are my options if I want to copy the volumes to another
> > > server (hopefully only the changed files) without stopping the VM. The
> > > rsync does not have to be atomic, it is OK if DomU writes some data after
> > > I start rsync.
> > >
> > > _______________________________________________
> > > Xen-users mailing list
> > > Xen-users@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-users
> > >       
>
>   



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