How to take instance live backup with out freezing

asked 2016-11-06 10:33:08 -0600

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 -

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).
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Block commit time out with below error [#virsh blockcommit instance-000000a5 vda --active --verbose --pivot]

error: block copy still active: disk 'vda' not ready for pivot yet
chamaraT gravatar imagechamaraT ( 2016-11-08 04:34:25 -0600 )edit