[Openstack-operators] Any serious stability and performance issues on RBD as ephemeral storage ?
mriedem at linux.vnet.ibm.com
Thu Dec 8 15:43:55 UTC 2016
On 12/7/2016 9:25 AM, Jonathan Proulx wrote:
> We've been using Ceph as ephemeral backend (and glance store and
> cinder backend) for > 2 years (maybe 3 ) and have been very happy.
> cinder has been rock solid on RBD side. Early on when we had 6 osd
> servers we lost one in production to a memory error. 1/6 is a large
> fraction to loose but Ceph handled it as designed and there was not
> noticable impact to any running instances.
> The ability to start VMs from snap shot of a glance image (which is
> how it's implemented if glance and nova are both cinder backed) makes
> start up super fast.
> Having shared storage also make live migration easy so we can do
> hardware maintenence (kernel and OS upgrades) without impacting
> running VMs
> As of Mitaka snapshotting running VMs is also fast, though for
> earlier releases VMs we suspended while the running RBD volumes was
> copied down to the the hypervisors and then restarted while the
> downloaded images was re-uploaded from the hypervisor to glance and
> back into Ceph. This could mean VMs down foro 15min or more if they
> had large root volumes. As I said this got fixed in Mitaka so if
> you're current this is no longer a problem.
This is the specific change mentioned above:
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