[Openstack-operators] max_age and until_refresh for fixing Nova quotas

Sam Morrison sorrison at gmail.com
Fri Mar 20 10:18:47 UTC 2015


We’ve had the following for a year or so but doesn’t help much, we still see it occurring every 10 mins or so.

max_age = 10
until_refresh = 5
reservation_expire=600

We have a cron job that runs every 10 mins that figures out what projects are out of sync and corrects them.
We’ve always been scared of setting these to zero but we probably should.

Sam


> On 15 Mar 2015, at 2:53 pm, Mike Dorman <mdorman at godaddy.com> wrote:
> 
> Yeah the default is just ‘0’ for both, which disables the refresh.
> 
> 
> 
> The one downside is that it may not be 100% transparent to the user.  If 
> the quota is already (incorrectly) too high, and exceeding the quota 
> limit, the reservation that triggers the refresh will still fail.  I.e. 
> the reservation is attempted based on the quota usage values _before_ the 
> refresh.  But then after that the quota should be fixed and it will work 
> again on the next reservation.
> 
> But my thinking is that most quota issues happen slowly over time.  If we 
> are correcting them often and automatically, they hopefully never get to 
> the point where they’re bad enough to manifest reservation errors to the 
> user.
> 
> I don’t have any information re: db load.  I assume it regenerates based 
> on what’s in the instances or reservations table.  I imagine the load for 
> doing a single refresh is probably comparable to doing a ‘nova list’.
> 
> Mike
> 
> 
> 
> On 3/14/15, 2:27 PM, "Tim Bell" <Tim.Bell at cern.ch> wrote:
> 
>> Interesting... what are the defaults ?
>> 
>> Assuming no massive DB load, getting synced within a day would seem 
>> reasonable. Is the default no max age ?
>> 
>> Tim
>> 
>>> -----Original Message-----
>>> From: Jesse Keating [mailto:jlk at bluebox.net]
>>> Sent: 14 March 2015 16:59
>>> To: openstack-operators at lists.openstack.org
>>> Subject: Re: [Openstack-operators] max_age and until_refresh for fixing 
>>> Nova
>>> quotas
>>> 
>>> On 3/14/15 8:11 AM, Mike Dorman wrote:
>>>> I did short write-up here http://t.co/Q5X1hTgJG1 if you are interested
>>>> in the details.
>>>> 
>>> 
>>> Thanks for sharing Matt! That's an excellent write up.
>>> 
>>> --
>>> -jlk
>>> 
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