Open Stack

On 10/07/2013 05:30 PM, Joshua Harlow wrote:
> A scenario that I've seen:
>
> Take 'nova-compute' down for software upgrade, API still accessible since
> you want to provide API uptime (aka not taking the whole cluster offline).
>
> User Y deletes VM on that hypervisor where nova-compute is currently down,
> DB locally deletes, at this point VM 'A' is still active but nova thinks
> its not.

Isn't this sort of thing exactly what "nova host-update --maintenance 
enable <hostname>" was intended for?  I.e., push all the VMs off that 
compute node so you can take down the services without causing problems.

Its kind of a pain that the host-update stuff is implemented at the 
hypervisor level though (and isn't available for libvirt), it seems like 
it could be implemented at a more generic level.  (And on that note, why 
isn't there a "host" table in the database since we can have multiple 
services running on one host and we might want to take them all down?)

Alternately, maybe we need to have a 2-stage delete, where the VM gets 
put into a "zombie" state in the database and the resources can't be 
reused until the compute service confirms that the VM has been killed.

Chris