We are looking for a daily instance backup mechanism for our cloud instances with out any disturbances to the availability. At the moment when taking snapshots it freezes the file system for some duration which seems to be based on the root file system size.
OS- CentOS 7 (Juno)
Reinstalled the QEMU using qemu-kvm-rhev repo (yum install qemu-kvm-ev.x86_64)
virsh version ->
Compiled against library: libvirt 1.2.8
Using library: libvirt 1.2.8
Using API: QEMU 1.2.8
Running hypervisor: QEMU 2.3.0
Tried to use the external snapshotting facility which is given by the Libvirt but it hangs on pivot phase. (REF - https://kashyapc.fedorapeople.org/virt/infra.next-2015/Advanced-Snapshots-with-libvirt-and-QEMU.pdf)
Below are the steps taken to get snapshot using libvirt external snapshotting and results are as below
Before taking snapshot
# virsh domblklist instance-000000a5 --details
Type Device Target Source
------------------------------------------------
file disk vda /var/lib/nova/instances/180f7bea-339f-46f7-8521-0fd3ad00af25/disk
Taking snapshot
# virsh snapshot-create-as instance-000000a5 instance-000000a5-snap8 "snap1 description" --diskspec vda,file=/tmp/snap8-testvm.qcow2 --disk-only --atomic --no-metadata
Domain snapshot instance-000000a5-snap8 created
# virsh domblklist instance-000000a5 --details
Type Device Target Source
------------------------------------------------
file disk vda /tmp/snap8-testvm.qcow2
After taking backup of "/var/lib/nova/instances/180f7bea-339f-46f7-8521-0fd3ad00af25/disk" executed the below command to merge snapshot with base.
#virsh blockcommit instance-000000a5 vda --active --verbose --pivot
Block Commit: [100 %]
This output hangs as above
On nova log in compute node -> 2016-11-06 21:47:08.622 16994 INFO nova.compute.manager [-] [instance: 180f7bea-339f-46f7-8521-0fd3ad00af25] VM Paused (Lifecycle Event)
2016-11-06 21:47:09.051 16994 WARNING nova.compute.manager [-] [instance: 180f7bea-339f-46f7-8521-0fd3ad00af25] Instance is paused unexpectedly. Ignore.
So Is it not possible to use LibVirt external snapshotting for Openstack ? Or what is the available method for taking live instance backups with out any disturbances to the availability. (At the moment we are not using LVM for storage so LVM backup will not be a option for us).