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[virt-tools-list] Re: [BackupPC-users] pre/post backup script for KVM guests

Very handy, Daniel, thank you.

Why do it this way?  That is, why not back up the VMs like any other server?


On Monday 19 October 2009 14:02:58 Daniel Berteaud wrote:
> Hi everyone.
> I've written a script to backup virtual machines managed by libvirt
> (only tested with KVM guests, but should works for Xen too, maybe others
> as well).
> It's called virt-backup.pl
> I've written it for integration with BackupPC:
> - take a dump of a VM in using the pre-backup facility
> - backup the dumps using BackupPC
> - cleanup the dumps in the post-backup phase
> This script can be used outside of BackupPC as it's quite generic.
> There are two main mode for this script:
> --pre: take the backup of the VM. This is called --pre because I use it
> as a pre-backup script for BackupPC
> --post: cleanup the dumps
> Here're some functionalities:
> - no configuration file needed, everything can be passed as command line
> arg
> - can take snapshots of virtual disks if they are on LVM Logical volume
> (the default is to try LVM in any case, if it's not possible, then, just
> dump the block device/file)
> - Supports backup of running VM with minimal downtime (if each virtual
> disks can be snapshoted, just resume the VM immediately resulting in
> just a few seconds of downtime, then, dump the snapshots. If snapshots
> are not available, the guest is suspended during the dump)
> - can save the state of running vm (equivalent of virsh save/virsh
> restore). This is optional because it's still not very reliable, and
> sometimes the restoration fails, leaving a crashed qemu process running
> and eating CPU cycles.
> - Can compress on-the-fly the virtual disks dumps
> (gzip,bzip2,pbzip2,lzop,xz)
> - Support virtual disks exclusions (if you want to backup the system
> disk of a VM, but not the data one for example)
> - Can work on installations where virtual disks are stored on one hosts,
> and guests runs on another on (NFS, iscsi etc... in any case, the script
> must be run on the host which holds the virtual disks)
> - Can backup as many guests as you want in one run (they'll be dumped
> sequentially)
> - Backups are run with low priority (nice and ionice), so it should'nt
> slow down too much your system.
> Here are the dependencies for this script to work
> - Sys::Virt perl module
> - XML::Simple per module
> - Getopt::Long perl module
> - lvm2
> - gzip (optional)
> - bzip2 (optional)
> - pbzip2 (optional)
> - lzop (optional)
> - xz (optional)
> You can run this script without argument to see the help. Edit it if you
> want more informations (there are some examples on how to use it at the
> beginning of the script).
> The script can be found here:
> http://repo.firewall-services.com/misc/virt-backup.pl
> Regards, Daniel

"I have never killed a man, but I have read many obituaries with great
   -- Clarence Darrow

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