How to Backup a Hypervisor
There are essentially three steps to fully backing up a hypervisor:
1) Create snapshots of all images
2) Create a tarball of the /var/lib/libvirt directory
3) Create a tarball of the /etc/libvirt directory
The second and third steps are self explainatory, so I am only going over step 1. :)
In order to create a snapshot of an image it needs to have a qcow2 image format.
To determine the volume format type, go into the directory where the images are:
cd /var/lib/libvirt/images/
Then determine the volume format type using qemu-img info:
qemu-img info my_image
image: my_image file format: qcow2 <==== This is the disk/image format virtual size: 10G (10737418240 bytes) disk size: 8.9G cluster_size: 65536
You take a snapshot like this:
virsh snapshot-create-as my_image my_image_snapshot1
Where "my_image" is the domain name and "my_image_snapshot1" is the name that I am giving the snapshot.
All the snapshots are stored as an xml file here:
/var/lib/libvirt/qemu/snapshot/
You can also see a list of snapshots for a particular domain by typing:
virsh snapshot-list my_image
Name Creation Time State
------------------------------------------------------------
my_image_snapshot1 2014-09-30 16:36:51 -0700 running
To convert the image from another format type to qcow2 (using my_image as an example):
qemu-img info my_image
image: my_image file format: raw virtual size: 10G (10737418240 bytes) disk size: 8.9G cluster_size: 65536
You have to power off the domain first:
virsh shutdown my_image
Next, convert my_image from raw to qcow2:
cd /var/lib/libvirt/images/
qemu-img convert -f raw my_image -O qcow2 my_image.qcow2
Then edit the xml file:
virsh edit my_image
Change this:
<driver name='qemu' type='raw'/>
To this:
<driver name='qemu' type='qcow2'/>
Save and quit.
virsh start my_image
I have a cron job that runs this script I wrote to back up the hypervisor monthly:
#!/bin/bash
IMAGEDIR=/var/lib/libvirt/images/ BACKUPDIR=/var/backup/home/data/
# Check to see if image format is qcow2 and if so create a snapshot:
for HOST in `ls -l $IMAGEDIR`;do FORMAT=`qemu-img info $HOST | grep format | cut -d' ' -f3` if ["$FORMAT" == "qcow2"];then virsh snapshot-create-as $HOST $HOST_1 fi done
tar -czvf $BACKUPDIR/var_libvirt.tar.gz /var/lib/libvirt
tar -czvf $BACKUPDIR/etc_libvirt.tar.gz /etc/libvirt
References: http://fedoraproject.org/wiki/Features/Virt_Live_Snapshots
http://kashyapc.com/2012/09/14/externaland-live-snapshots-with-libvirt/