[openstack-dev] [nova] should we have a stale data indication in "nova list/show"?

Joe Gordon joe.gordon0 at gmail.com
Wed Jun 25 18:49:34 UTC 2014

On Wed, Jun 25, 2014 at 11:26 AM, Day, Phil <philip.day at hp.com> wrote:

> > -----Original Message-----
> > From: Sean Dague [mailto:sean at dague.net]
> > Sent: 25 June 2014 11:49
> > To: OpenStack Development Mailing List (not for usage questions)
> > Subject: Re: [openstack-dev] [nova] should we have a stale data
> indication in
> > "nova list/show"?
> >
> > On 06/25/2014 04:28 AM, Belmiro Moreira wrote:
> > > I like the current behavior of not changing the VM state if
> > > nova-compute goes down.
> > >
> > > The cloud operators can identify the issue in the compute node and try
> > > to fix it without users noticing. Depending in the problem I can
> > > inform users if instances are affected and change the state if
> necessary.
> > >
> > > I wouldn't like is to expose any failure in nova-compute to users and
> > > be contacted because VM state changed.
> >
> > Agreed. Plus in the perfectly normal case of an upgrade of a compute node
> > it's expected that nova-compute is going to be down for some period of
> > time, and it's 100% expected that the VMs remain up and ACTIVE over that
> > period.
> >
> > Setting VMs to ERROR would totally gum that up.
> >
> +1 that the state shouldn't be changed.
> What about if we exposed the last updated time to users and allowed them
> to decide if its significant or not ?

I have changed my mind on this one. I agree we shouldn't change any state,
and I also do not think we should show the last update time to the user
either. I don't think showing that information would be very helpful to
users, if at all, and would train users to poll nova more.

We don't want folks using nova list/show to check if there instance is
functional or not.  A user should care about if there instance is operating
as expected, nova misbehaving isn't the only reason an instance may go
haywire (the service they are running inside the instance can crash etc.).
 So we should expect users to be able to monitor the health of there
instance without needing to poll nova on a regular basis.


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