Nice timing. I was working on a blog post on this topic. On 10/13/2014 05:40 PM, Fei Long Wang wrote: > I think Adam is talking about this bp: > https://blueprints.launchpad.net/nova/+spec/evacuate-instance-automatically > > For now, we're using Nagios probe/event to trigger the Nova evacuate > command, but I think it's possible to do that in Nova if we can find a > good way to define the trigger policy.
I actually think that's the right way to do it. There are a couple of other things to consider: 1) An ideal solution also includes fencing. When you evacuate, you want to make sure you've fenced the original compute node. You need to make absolutely sure that the same VM can't be running more than once, especially when the disks are backed by shared storage. Because of the fencing requirement, another option would be to use Pacemaker to orchestrate this whole thing. Historically Pacemaker hasn't been suitable to scale to the number of compute nodes an OpenStack deployment might have, but Pacemaker has a new feature called pacemaker_remote [1] that may be suitable. 2) Looking forward, there is a lot of demand for doing this on a per instance basis. We should decide on a best practice for allowing end users to indicate whether they would like their VMs automatically rescued by the infrastructure, or just left down in the case of a failure. It could be as simple as a special tag set on an instance [2]. [1] http://clusterlabs.org/doc/en-US/Pacemaker/1.1/html-single/Pacemaker_Remote/ [2] https://review.openstack.org/#/c/127281/ -- Russell Bryant _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
