[Openstack] nova backup - instances unreachable

Eugen Block eblock at nde.ag
Wed Jan 11 08:32:47 UTC 2017


this seems to be exptected, the docs say:

"Shut down the source VM before you take the snapshot to ensure that  
all data is flushed to disk."

So if the VM is not shut down, it's freezed to prevent data loss (I  
guess). Depending on your storage backend, there are other ways to  
perform backups of your VMs.
We use Ceph as backend for nova, glance and cinder. Ceph stores the  
disks, images and volumes as Rados block device objects. We have a  
backup script that creates snapshots of these RBDs, which are exported  
to our backup drive. This way the running VM is not stopped or  
freezed, the user doesn't notice any issues. Unlike a nova snapshot,  
the rbd snapshot is created immediately within a few seconds. After a  
successful backup the snapshots are removed.

Hope this helps! If you are interested in Ceph, visit [1].


[1] http://docs.ceph.com/docs/giant/start/intro/

Zitat von John Petrini <jpetrini at coredial.com>:

> Hello,
> I've just started experimenting with nova backup and discovered that there
> is a period of time during the snapshot where the instance becomes
> unreachable. Is this behavior expected during a live snapshot? Is there any
> way to prevent this?
> ___
> John Petrini

Eugen Block                             voice   : +49-40-559 51 75
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