On Tue, Jun 24, 2014 at 4:16 PM, Ahmed RAHAL <[email protected]> wrote:
> Le 2014-06-24 17:38, Joe Gordon a écrit : > >> >> On Jun 24, 2014 2:31 PM, "Russell Bryant" <[email protected] >> <mailto:[email protected]>> wrote: >> > > > There be dragons here. Just because Nova doesn't see the node >> reporting >> > in, doesn't mean the VMs aren't actually still running. I think this >> > needs to be left to logic outside of Nova. >> > >> > For example, if your deployment monitoring really does think the host >> is >> > down, you want to make sure it's *completely* dead before taking >> further >> > action such as evacuating the host. You certainly don't want to risk >> > having the VM running on two different hosts. This is just a business >> I >> > don't think Nova should be getting in to. >> >> I agree nova shouldn't take any actions. But I don't think leaving an >> instance as 'active' is right either. I was thinking move instance to >> error state (maybe an unknown state would be more accurate) and let the >> user deal with it, versus just letting the user deal with everything. >> Since nova knows something *may* be wrong shouldn't we convey that to >> the user (I'm not 100% sure we should myself). >> > > I saw compute nodes going down, from a management perspective (say, > nova-compute disappeared), but VMs were just fine. Reporting on the state > may be misleading. The 'unknown' state would fit, but nothing lets us > presume the VMs are non-functional or impacted. > nothing lets us presume the opposite as well. We don't know if the instance is still up. > > As far as an operator is concerned, a compute node not responding is a > reason enough to check the situation. > > To go further about other comments related to customer feedback, there are > many reasons a customer may think his VM is down, so showing him a 'useful > information' in some cases will only trigger more anxiety. > Besides people will start hammering the API to check 'state' instead of > using proper monitoring. > But, state is already reported if the customer shuts down a VM, so ... > > Currently, compute nodes state reporting is done by the nova-compute > process himself, reporting back with a time stamp to the database (through > conductor if I recall well). It's more like a watchdog than a reporting > system. > For VMs (assuming we find it useful) the same kind of process could occur: > nova-compute reporting back all states with time stamps for all VMs he > hosts. This shall then be optional, as I already sense scaling/performance > issues here (ceilometer anyone ?). > > Finally, assuming the customer had access to this 'unknown' state > information, what would he be able to do with it ? Usually he has no lever > to 'evacuate' or 'recover' the VM. All he could do is spawn another > instance to replace the lost one. But only if the VM really is currently > unavailable, an information he must get from other sources. > If I was a user, and my instance went to an 'UNKNOWN' state, I would check if its still operating, and if not delete it and start another instance. > > So, I see how the state reporting could be a useful information, but am > not sure that nova Status is the right place for it. > > Ahmed. > > > _______________________________________________ > OpenStack-dev mailing list > [email protected] > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >
_______________________________________________ OpenStack-dev mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
