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

[Tyler J. Wagner]

Very handy, Daniel, thank you.

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

Regards,
Tyler

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
> 

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