Hi All.
I have installed Citrix XenServer. It's Linux-based virtualization software. Could anyone propose a good way to make backups of virtual machines (Linux/Windows) in it?
With regards, R.
Rafał Radecki sent a missive on 2010-02-05:
Hi All.
I have installed Citrix XenServer. It's Linux-based virtualization software. Could anyone propose a good way to make backups of virtual machines (Linux/Windows) in it?
With regards, R.
Do you have any shared storage that you're using which supports snapshots? If you do, then a combination of coalescing the running VM's to disk and taking a snap and also using traditional backup methods (application aware) to disk/tape for archival and complete failure of the storage is a reasonable thing to do.
S.
2010/2/5 Simon Billis simon@houxou.com
Do you have any shared storage that you're using which supports snapshots? If you do, then a combination of coalescing the running VM's to disk and taking a snap and also using traditional backup methods (application aware) to disk/tape for archival and complete failure of the storage is a reasonable thing to do.
S.
the main problem with this, is that one client on that VM (think about shared hosting accounts on the VM) wants to restore a single file, or a few files, then you're going to have to restore the whole snapshot and a lot of other files will be lost.
I'm experimenting with an NFS mount from our backup server. Basically, export the NFS share, and mount it inside the VM, then use your favorite backup procedure / software. For our cPanel VM's, we use cPanel's native backup function which makes use of rsync - and allows us to restore a single file if needed. For other VM's without a control panel, rsync also works well.
Rudi Ahlers wrote:
2010/2/5 Simon Billis <simon@houxou.com mailto:simon@houxou.com>
Do you have any shared storage that you're using which supports snapshots? If you do, then a combination of coalescing the running VM's to disk and taking a snap and also using traditional backup methods (application aware) to disk/tape for archival and complete failure of the storage is a reasonable thing to do. S.the main problem with this, is that one client on that VM (think about shared hosting accounts on the VM) wants to restore a single file, or a few files, then you're going to have to restore the whole snapshot and a lot of other files will be lost.
I'm experimenting with an NFS mount from our backup server. Basically, export the NFS share, and mount it inside the VM, then use your favorite backup procedure / software. For our cPanel VM's, we use cPanel's native backup function which makes use of rsync - and allows us to restore a single file if needed. For other VM's without a control panel, rsync also works well.
For file by file backups, I always recommend backuppc as the first choice, especially in a situation where you have several hosts containing copies of the same files since backuppc will pool all the duplicates in its storage. Of course you may also want some less frequent image copies of the host for faster restores if you need to rebuild from scratch.
Rudi Ahlers sent a missive on 2010-02-07:
2010/2/5 Simon Billis simon@houxou.com Do you have any shared storage that you're using which supports snapshots? If you do, then a combination of coalescing the running VM's to disk and taking a snap and also using traditional backup methods (application aware) to disk/tape for archival and complete failure of the storage is a reasonable thing to do.
the main problem with this, is that one client on that VM (think about shared hosting accounts on the VM) wants to restore a single file, or a few files, then you're going to have to restore the whole snapshot and a lot of other files will be lost.
Not necessarily, some storage will allow the mounting of a snap as readonly specifically to allow for this type of restore. The storage will also allow for the snap to be R/W or duplicated and to be allocated to another host to become a live machine.
I'm experimenting with an NFS mount from our backup server. Basically, export the NFS share, and mount it inside the VM, then use your favorite backup procedure / software. For our cPanel VM's, we use cPanel's native backup function which makes use of rsync - and allows us to restore a single file if needed. For other VM's without a control panel, rsync also works well.
I've had mixed results with NFS, sometimes under high loading it would fail and usually when I was in the process of backing up a few machines (four or more) at once to the NFS server.
Good quality storage (which usually comes at a price) will provide the functionality that is needed to backup the VM's either as a complete VM image or files from the VM filesystem. Entry level storage from suppliers such as Equallogic/Dell comes with this functionality and it is possible to have the storage up and attached to servers within 10 mins from un-boxing it (but do allow a little longer to understand it ;-) .)
I do believe that all backup strategies need to be examined frequently to ensure that they have met and are meeting your needs as the requirement often changes when new applications are rolled out or the usage of an existing application changes.
S.
Simon Billis wrote:
Good quality storage (which usually comes at a price) will provide the functionality that is needed to backup the VM's either as a complete VM image or files from the VM filesystem. Entry level storage from suppliers such as Equallogic/Dell comes with this functionality and it is possible to have the storage up and attached to servers within 10 mins from un-boxing it (but do allow a little longer to understand it ;-) .)
Suggest reading this interesting piece "3 years of equallogic" before thinking about using it's snapshot stuff -
http://www.tuxyturvy.com/blog/index.php?/archives/61-Three-Years-of-Equallog...
Of course not all snapshot solutions are created equal, equallogic's appears to be especially poor in this regard.
nate
On Mon, 8 Feb 2010, nate wrote:
Suggest reading this interesting piece "3 years of equallogic" before thinking about using it's snapshot stuff -
http://www.tuxyturvy.com/blog/index.php?/archives/61-Three-Years-of-Equallog...
If you do snapshotting at the OS level, i.e. LVM snapshots or ZFS snapshots than EQ is a pretty nice piece of equipment, otherwise, don't even get me started. :)
On Mon, Feb 08, 2010 at 12:07:30PM -0800, nate wrote:
Simon Billis wrote:
Good quality storage (which usually comes at a price) will provide the functionality that is needed to backup the VM's either as a complete VM image or files from the VM filesystem. Entry level storage from suppliers such as Equallogic/Dell comes with this functionality and it is possible to have the storage up and attached to servers within 10 mins from un-boxing it (but do allow a little longer to understand it ;-) .)
Suggest reading this interesting piece "3 years of equallogic" before thinking about using it's snapshot stuff -
http://www.tuxyturvy.com/blog/index.php?/archives/61-Three-Years-of-Equallog...
Of course not all snapshot solutions are created equal, equallogic's appears to be especially poor in this regard.
I think that blog post gives too negative view of the EQL snapshots. They work very well for many use cases. Having a lot of random small writes all over the volume seems to cause a lot of wasted disk space though.
-- Pasi
Pasi Kärkkäinen sent a missive on 2010-02-09:
On Mon, Feb 08, 2010 at 12:07:30PM -0800, nate wrote:
Simon Billis wrote:
Good quality storage (which usually comes at a price) will provide the functionality that is needed to backup the VM's either as a complete VM image or files from the VM filesystem. Entry level storage from suppliers such as Equallogic/Dell comes with this functionality and it is possible to have the storage up and attached to servers within 10 mins from un-boxing it (but do allow a little longer to understand it ;-) .)
Suggest reading this interesting piece "3 years of equallogic" before thinking about using it's snapshot stuff -
http://www.tuxyturvy.com/blog/index.php?/archives/61-Three-Years-of- Eq uallogic.html
Of course not all snapshot solutions are created equal, equallogic's appears to be especially poor in this regard.
I think that blog post gives too negative view of the EQL snapshots. They work very well for many use cases. Having a lot of random small writes all over the volume seems to cause a lot of wasted disk space though.
I agree - I'm not suggesting that the EQL box is the best thing since sliced bread, but it does what it says on the tin. There are better/different arrays and array controllers out there (3par, BlueArc, Pillar, EMC, Hitachi etc., etc., etc.,) and depending on your needs and budget both now and in the future and it would be wise to select the one that provides the best fit for you and your business.
If the goal is to backup the VMs rather than the Citrix XenServer Dom0, I find that exporting each VM to a shared disk (NFS, iSCSI, whatever) is the easiest solution. If you need zero-downtime, then make a snapshot of the VM and then export it.
I did this specifically for the purpose of disaster recovery. Recovering individual files or datasets from within a VM is also possible but is slightly more of a hassle.
I have some scripts that do this that I'm willing to share.
BTW... Centos and Citrix XenServer are different enough that these kinds of questions should probably be asked on the XenSource mailing list or the Citrix forums. You can get potentially misleading advice otherwise.
-geoff
--------------------------------- Geoff Galitz Blankenheim NRW, Germany http://www.galitz.org/ http://german-way.com/blog/
2010/2/5 Rafał Radecki radecki.rafal@gmail.com:
I have installed Citrix XenServer. It's Linux-based virtualization software. Could anyone propose a good way to make backups of virtual machines (Linux/Windows) in it?
Try the XenServer mailing lists or wiki?
http://wiki.xensource.com/xenwiki/ http://lists.xensource.com/
Ben
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On 05/02/2010 15:23, Rafał Radecki wrote:
Hi All.
I have installed Citrix XenServer. It's Linux-based virtualization software. Could anyone propose a good way to make backups of virtual machines (Linux/Windows) in it?
One way to do it is to not treat virtual machines in a special way. This means: imagine the virtual machine is physical ;-) Or in other words: Back it up like every other machine.
- -- best regards, markus
-
Benjamin Donnachie -
Geoff Galitz -
James A. Peltier -
Les Mikesell -
Markus Falb -
nate -
Pasi Kärkkäinen -
Rafał Radecki -
Rudi Ahlers -
Simon Billis