On 06/11/15 at 06:54pm, Ian Wells wrote:
On 11 June 2015 at 12:37, Richard Raseley <rich...@raseley.com> wrote:
Andrew Laski wrote:
There are many reasons a deployer may want to live-migrate instances
around: capacity planning, security patching, noisy neighbors, host
maintenance, etc... and I just don't think the user needs to know or
care that it has taken place.
They might care, insofar as live migrations will often cause performance
degradation from a users perspective.
Seconded. If your app manager is warned that you're going to be live
migrating it can do something about the capacity drop. I can imagine cases
where a migrating VM would be brutally murdered [1] and replaced because
it's not delivering sufficient performance.
To be clear I see instance-action reporting more as a log of what has
previously happened to an instance, not a report of what's currently
happening. A live migration still has task_state changes to make it
visible to a user.
My view is that in a cloud environment it shouldn't matter which host
you're on, as long as it meets the scheduling constraints required, so a
no-downtime movement between them is not an important event for a user.
But that does ignore the performance drop-off that may be noticed by a
user, so there are reasons to expose that information. I'm just in
favor of making it optional, not hiding it in general.
--
Ian.
[1] See "nova help brutally-murder"
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