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Re: [Xen-users] Backup domU

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Subject: Re: [Xen-users] Backup domU
From: Steve Allison <xen-users@xxxxxxxxxxxxxxxxxx>
Date: Sat, 09 Jul 2011 10:26:49 +0100
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On 09/07/2011 08:54, Simon Hobson wrote:
Kalil Costa - Brasilsite wrote:

The backup is also on the same disks as the live system.

I don't know why you make this point, as, at least in this thread, the target of the backup is not mentioned and is trivial to have it point to another system.

Personally I backup my guests as though they were real (non virtualised) machines. There are many options for this - both free and commercial.

At work I've setup a system where I have a VM dedicated just to holding backups of the other machines - each of which uses rsync to update a backup copy of itself on the backup server (the server runs rsync in server mode). Thus I have a server holding a complete image of each of my servers at the point they last backed up. Should a host go down, I can move the guests to another host by creating volumes for them and using rsync to pull their files back (mount the guest filesystems on the host, use rsync on the host to pull the files, unmount the filesystems and start the guest). Of course, once you are using rsync, then it doesnt' matter whether the destination is on the same host, another host in the same rack, or half way round the world - as long as you have enough bandwidth.

On my backup machine I then copy the copies to create various levels of historical backups. Again there are various ways of doing this, I settled on StoreBackup which if you disable compression creates full copies which you can just navigate into and use your normal unix/linux tools to access files*. It saves space by hard-linking identical files so it's fairly efficient. You can do something similar with rsync and some scripting. Another tool I looked at was rdiff-backup - but I didn't like the way you can't thin out your backups, and they aren't readable without going through the restore process.

A perfect tool for this is backuppc. http://backuppc.sourceforge.net/

Quick summary of benefits,
 - rsync, smb, ftp support
 - uses hardlinks to create incremental backups,
- reduces disk space further by compressing and only storing one copy of each file across all backups (generates hashes of new files nightly to determine duplicates) - We have 29 hosts backed up nightly, with historical backups of some going back 13 months. Available data in full: 491GB, actual stored space: 65GB
 - full set of cmdline tools to manipulate backups
 - restore is trivially easy
 - web interface gives statistics
 - retries failed attempts
 - mails you if a machine is not backed up for X hours.
- can give user web access to just their own backups (we don't use this though, I beleive no web interface is safe)

May the ping be with you ..

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