[Openstack-operators] limit num instance-type per host

Marcos Garcia marcos.garcia at enovance.com
Wed Sep 24 15:18:12 UTC 2014

Hello Blair

IMO it's a matter of capacity planning and design to minimize 
fragmentation. I don't know of any mechanisms to filter this and solve 
(i.e. re-balance) a posteriori. Blueprints exists, though, to allow 
re-scheduling and re-balancing.

Maybe I'm wrong and there are indeed some scheduler filters out of the 

Anyways, I recommend you to read this: 
and open this spreadsheet: 
https://github.com/noslzzp/cloud-resource-calculator , it will show you 
the optimal flavor configuration for minimal fragmetation using 
different variables (vcpu, RAM, disk)


On 2014-09-24 11:08 AM, Blair Bethwaite wrote:
> Hi all,
> I'm trying to wrap my head around whether it's possible with the 
> existing scheduler filters, to put a limit per host on the number of 
> instances per instance-type/flavor? I don't think this is possible 
> with the existing filters or weights, but it seems like a fairly 
> common requirement.
> The issue I'm thinking of using this for is that of instance-to-host 
> fragmentation in homogenous deployments, where there is a tendency as 
> the zone approaches capacity to hit a utilisation ceiling - there are 
> rarely any "gaps" large enough for high vcpu count instances. I'm 
> guessing that limiting the number of smaller instances per host would 
> help to alleviate this.
> Looks like knocking up such a filter wouldn't be too hard, just want 
> to check whether there is another way...?
> -- 
> Cheers,
> ~Blairo
> _______________________________________________
> OpenStack-operators mailing list
> OpenStack-operators at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators


*Marcos Garcia
Technical Sales Engineer

*PHONE : *(514) – 907 - 0068 *EMAIL :*marcos.garcia at enovance.com 
<mailto:marcos.garcia at enovance.com> - *SKYPE : *enovance-marcos.garcia**
*ADDRESS :*127 St-Pierre – Montréal (QC) H2Y 2L6, Canada *WEB : 
*www.enovance.com <http://www.enovance.com/>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-operators/attachments/20140924/44906d64/attachment.html>

More information about the OpenStack-operators mailing list