[openstack-dev] [Nova] [Neutron] heal_instance_info_cache_interval - Can we kill it?

Aaron Rosen aaronorosen at gmail.com
Wed May 28 04:55:38 UTC 2014


Hi,

Sorry somehow I missed this email. I don't think you want to disable it,
though we can definitely have it run less often. The issue with disabling
it is if one of the notifications from neutron->nova never gets sent
successfully to nova (neutron-server is restarted before the event is sent
or some other internal failure). Nova will never update it's cache if
the heal_instance_info_cache_interval is set to 0.  The neutron->nova
events help to ensure that the nova info_cache is up to date sooner by
having neutron inform nova whenever a port's data has changed (@Joe Gordon
- this happens regardless of virt driver).

If you're using the libvirt virt driver the neutron->nova events will also
be used to ensure that the networking is 'ready' before the instance is
powered on.

Best,

Aaron

P.S: we're working on making the heal_network call to neutron a lot less
expensive as well in the future.




On Tue, May 27, 2014 at 7:25 PM, Joe Gordon <joe.gordon0 at gmail.com> wrote:

>
>
>
> On Wed, May 21, 2014 at 6:21 AM, Assaf Muller <amuller at redhat.com> wrote:
>
>> Dear Nova aficionados,
>>
>> Please make sure I understand this correctly:
>> Each nova compute instance selects a single VM out of all of the VMs
>> that it hosts, and every <heal_instance_info_cache_interval> seconds
>> queries Neutron for all of its networking information, then updates
>> Nova's DB.
>>
>> If the information above is correct, then I fail to see how that
>> is in anyway useful. For example, for a compute node hosting 20 VMs,
>> it would take 20 minutes to update the last one. Seems unacceptable
>> to me.
>>
>> Considering Icehouse's Neutron to Nova notifications, my question
>> is if we can change the default to 0 (Disable the feature), deprecate
>> it, then delete it in the K cycle. Is there a good reason not to do this?
>>
>
> Based on the patch that introduced this function [0] you may be on to
> something, but AFAIK unfortunately the neutron to nova notifications only
> work in libvirt right now [1], so I don' think we can fully deprecate this
> periodic task. That being said turning it off by default may be an option.
> Have you tried disabling this feature and seeing what happens (in the gate
> and/or in production)?
>
>
> [0] https://review.openstack.org/#/c/4269/
> [1] https://wiki.openstack.org/wiki/ReleaseNotes/Icehouse
>
>
>>
>>
>> Assaf Muller, Cloud Networking Engineer
>> Red Hat
>>
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>>
>
>
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