[Openstack-operators] over commit ratios

Erik McCormick emccormick at cirrusseven.com
Tue Apr 21 20:12:34 UTC 2015

We had this discussion at the Ops Mid-Cycle meetup. I think the general
consensus was 0.9 for memory. if you're running Ceph OSD's on the node
you'll almost certainly want to reserve more than a gig for it and the OS.

for CPU there was a wide range of ideas and it mainly depended on use-case.
If you're running lots of CPU-intensive things like Hadoop, better to be
around 2 or even 1. If you've got a ton of web servers, you could go with
16 easily. If you've got a mixed-use cloud, some segregation with host
aggregates may be helpful so you can vary the number. If you can't do that
though, and you're mixed, you should be able to go better than 2. At least
5 should be OK unless you've packed a massive amount of memory in each node.


On Tue, Apr 21, 2015 at 3:59 PM, Caius Howcroft <caius.howcroft at gmail.com>

> Just a general question: what kind of over commit ratios do people
> normally run in production with?
> We currently run 2 for cpu and 1 for memory (with some held back for
> OS/ceph)
> i.e.:
> default['bcpc']['nova']['ram_allocation_ratio'] = 1.0
> default['bcpc']['nova']['reserved_host_memory_mb'] = 1024 # often larger
> default['bcpc']['nova']['cpu_allocation_ratio'] = 2.0
> Caius
> --
> Caius Howcroft
> @caiushowcroft
> http://www.linkedin.com/in/caius
> _______________________________________________
> OpenStack-operators mailing list
> OpenStack-operators at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-operators/attachments/20150421/ef8b3553/attachment.html>

More information about the OpenStack-operators mailing list