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

Chris Friesen chris.friesen at windriver.com
Wed Sep 20 19:49:28 UTC 2017

On 09/20/2017 12:47 PM, Matt Riedemann wrote:

> I wanted to bring it up here in case anyone had a good reason why we should not
> continue to exclude originally failed hosts during live migration, even if the
> admin is specifying one of those hosts for the live migration destination.
> 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).

As you say, a failure on a host during the original instance creation (which 
could have been a long time ago) is not a reason to bypass that host during 
subsequent operations.

In other words, I think the list of hosts to ignore should be scoped to a single 
"operation" that requires scheduling (which would include any necessary 
rescheduling for that "operation").


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