Backup Virtual Machine

Jeff — Sun, 11 Nov 2018 08:21:51 +0000

Backup Virtual Machine Jeff Sun, 11/11/2018 - 10:21

Sources:

1. As root, locate the virtual machine you want to back up using virsh:

virsh -c qemu:///system list # shows only running

virsh list --all # shows all

2. Dump the configuration for your virtual machine:

virsh -c qemu:///system dumpxml MACHINE_NAME > /var/lib/libvirt/images/safe/MACHINE_NAME.datestamp.xml

3. You may need to locate the image directory:

virsh -c qemu:///system domblklist MACHINE_NAME

4. Now prepare the backup of this machine using a snapshot:

virsh snapshot-create-as --domain MACHINE_NAME IMAGE_NAME.snapshot --diskspec sda,file=/var/lib/libvirt/images/safe/IMAGE_NAME.snapshot.qcow2 --disk-only --atomic

Note: If you get an error, then the disk is not converted to virtio-scsi, and should be vda, not sda.

After creating the snapshot, all disk operations from the guest will be directed to it so that you can copy the original disk image to a safe place.

You can establish this by running, as example:

virsh -c qemu:///system domblklist ispa

Target     Source
------------------------------------------------
hda        -
sda        /var/lib/libvirt/images/safe/ispa.snapshot.qcow2

5. Copy to external server and include both the qcow2 disk image and the machine configuration (the XML file):

su - yourusername # you must be in libvirt-qemu group

rsync -hav --progress /var/lib/libvirt/images/IMAGE_NAME.qcow2 192.168.100.2:backups/ # IP address of prionyx on 1GB VLAN

6. Merge snapshot:

After the file transfer is completed, you should merge changes written to snapshot, back to original disk image. This operation is called 'active block commit':

virsh blockcommit MACHINE_NAME sda --active --pivot --shallow --verbose

Check block devices again. If the block commit completed successfuly your virtual machine should use its original image again.