Re: [Openstack-operators] [openstack-dev] [nova] Is there any reason to exclude originally failed build hosts during live migration?

[Sylvain Bauza]

On Wed, Sep 20, 2017 at 10:15 PM, melanie witt  wrote:

> On Wed, 20 Sep 2017 13:47:18 -0500, Matt Riedemann wrote:
>
>> Presumably there was a good reason why the instance failed to build on a
>> host originally, but that could be for any number of reasons: resource
>> claim failed during a race, configuration issues, etc. Since we don't
>> really know what originally happened, it seems reasonable to not exclude
>> originally attempted build targets since the scheduler filters should still
>> validate them during live migration (this is all assuming you're not using
>> the 'force' flag with live migration - and if you are, all bets are off).
>>
>
> Yeah, I think because an original failure to build could have been a
> failed claim during a race, config issue, or just been a very long time
> ago, we shouldn't continue to exclude those hosts forever.
>
> If people agree with doing this fix, then we also have to consider making
>> a similar fix for other move operations like cold migrate, evacuate and
>> unshelve. However, out of those other move operations, only cold migrate
>> attempts any retries. If evacuate or unshelve fail on the target host,
>> there is no retry.
>>
>
> I agree with doing that fix for all of the move operations.
>
>
Yeah, a host could be failing when we created that instance 1 year ago,
that doesn't mean the host won't be available this time.

> -melanie
>
>
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Re: [Openstack-operators] [openstack-dev] [nova] Is there any reason to exclude originally failed build hosts during live migration?

[melanie witt]

On Wed, 20 Sep 2017 13:47:18 -0500, Matt Riedemann wrote:
Presumably there was a good reason why the instance failed to build on a 
host originally, but that could be for any number of reasons: resource 
claim failed during a race, configuration issues, etc. Since we don't 
really know what originally happened, it seems reasonable to not exclude 
originally attempted build targets since the scheduler filters should 
still validate them during live migration (this is all assuming you're 
not using the 'force' flag with live migration - and if you are, all 
bets are off).


Yeah, I think because an original failure to build could have been a 
failed claim during a race, config issue, or just been a very long time 
ago, we shouldn't continue to exclude those hosts forever.


If people agree with doing this fix, then we also have to consider 
making a similar fix for other move operations like cold migrate, 
evacuate and unshelve. However, out of those other move operations, only 
cold migrate attempts any retries. If evacuate or unshelve fail on the 
target host, there is no retry.


I agree with doing that fix for all of the move operations.

-melanie

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