properly sizing openstack controlplane infrastructure

Hartwig Hauschild openstack at
Thu May 2 14:15:17 UTC 2019

Am 30.04.2019 schrieb Daniel Speichert:
> ----- Original Message -----
> > From: "Hartwig Hauschild" <openstack at>
> > To: openstack-discuss at
> > Sent: Tuesday, April 30, 2019 9:30:22 AM
> > Subject: properly sizing openstack controlplane infrastructure
> > The requirements we've got are basically "here's 50 compute-nodes, make sure
> > whatever you're building scales upwards from there".
> It depends what's your end goal. 100? 500? >1000 nodes?
> At some point things like Nova Cells will help (or become necessity).

I really hope not that high, but splitting into cells or AZs / Regions is
definitely planned if it goes up.

> > The pike-stack has three servers as control-plane, each of them with 96G of
> > RAM and they don't seem to have too much room left when coordinating 14
> > compute-nodes.
> 96 GB of RAM per controller is much more than enough for 14 compute nodes.
> There's room for improvement in configuration.
> > We're thinking about splitting the control-nodes into infrastructure
> > (db/rabbit/memcache) and API.
> > 
> > What would I want to look for when sizing those control-nodes? I've not been
> > able to find any references for this at all, just rather nebulous '8G RAM
> > should do' which is around what our rabbit currently inhales.
> You might want to check out Performance Docs:
> For configuration tips, I'd suggest looking at what openstack-ansible
> or similar projects provide as "battle-tested" configuration.
> It's a good baseline reference before you tune yourself.
Problem is: For all I know this is a non-tuned openstack-ansible-setup.

I guess I'll have to figure out why it's using way more memory than it
should (and run out every now and then).



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