[Openstack] ram_allocation_ratio per compute node or per AZ

Day, Phil philip.day at hp.com
Sat Dec 20 14:44:10 UTC 2014


Your problem is that you still have the original ram filter configured, so its still removing all of the hosts. Try removing that and you should be OK.  Note though that then any hosts not in an aggregate with a ram ratio set won't have a ram limit at all.

You might also find the aggregate filter causes problems if you have a lot of hosts, as it does a dB look up for each host per VM request.


On 20 Dec 2014 14:28, mad Engineer <themadengin33r at gmail.com> wrote:
Thanks Antonio,
                          I added AggregateRamFilter in nova.conf of
scheduler and restarted nova-scheduler service and updated aggregate.

nova aggregate-set-metadata id ram_allocation_ratio=2.08
and i can see that in

nova aggregate-details 2
| Id | Name          | Availability Zone | Hosts          | Metadata
| 2  | overcommitted | second             | 'node8' |
'availability_zone=second', 'ram_allocation_ratio=2.08' |
but still scheduler log shows
  "Filter AggregateRamFilter returned 1 host(s)"
" Filter RamFilter returned 0 hosts"
and fails with error "instances:17 does not have 2048 MB usable ram,
it only has 613.5 MB usable ram."

Any idea?

On Sat, Dec 20, 2014 at 3:09 PM, Antonio Messina
<antonio.s.messina at gmail.com> wrote:
> On Sat, Dec 20, 2014 at 8:47 AM, mad Engineer <themadengin33r at gmail.com> wrote:
>> Hello All,
>>               I would like to know if its possible to set
>> "ram_allocation_ratio" per compute node or at least per Availability
>> zone.
>> I tried setting that per compute nodes,but i get "no hosts found"
>> message when allocation ratio reaches default 1.5 .Changing it on
>> controller fixes this,but i dont want it to be set globally across all
>> AZ.Is it possible?
> As far as I know you can set this value only globally or per aggregate.
> In case you want to set it per host aggregate you have to enable
> AggregateRamFilter. I never tried, but I guess you have to set this
> value as an aggregate metadata, using
>     nova aggregate-set-metadata <id> ram_allocation_ratio=2
> If you test it and it works let us know please, I'm interested too but
> didn't have time to test it yet.
> .a.
> --
> antonio.s.messina at gmail.com
> antonio.messina at uzh.ch                     +41 (0)44 635 42 22
> S3IT: Service and Support for Science IT   http://www.s3it.uzh.ch/
> University of Zurich
> Winterthurerstrasse 190
> CH-8057 Zurich Switzerland

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