Re: [BackupPC-users] Backuppc and KVM virtual machine

[Carl C. <ccr...@ex...>]

The VM isn't an issue (my BackupPC has run in a KVM guest for over two years), but using "file-based" storage (a filesystem inside a file stored on another filesystem) is extremely inefficient (we recently ran benchmarks on file versus raw device... the performance is awful in comparison).

Use a raw device (raw disk, LVM volume, etc) with the virtio driver.  Your OS and backup storage can reside on the same raw device, or they can be separate raw devices, or if you insist, the OS can be virtual file storage.  We just use raw devices (LVM logical volumes) for everything.

My disk configuration looks like this (virsh dumpxml <guestname>):

     <disk type='block' device='disk'>
       <driver name='qemu' type='raw'/>
       <source dev='/dev/diskbackup/diskbackup'/>
       <target dev='vda' bus='virtio'/>
       <alias name='virtio-disk0'/>
       <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
     </disk>

"/dev/diskbackup/diskbackup" is a logical volume named "diskbackup" in a volume group named "diskbackup".  (I didn't configure this... traditionally, this would be "/dev/vgdiskbackup/lvdiskbackup" or such.)

-- 
Carl D Cravens (ccr...@ex...), Ext 228 (620.327.1228)
Lead System Architect