Open Stack

On 10/31/21 10:54 PM, A Monster wrote:
> I'm in the process of deploying an Openstack cloud and I've been aiming
> at maximize the number of computing node and in order to do that I've
> thought of using Ceph distributed storage and use an All in one
> openstack deployment, so that swift objects and glance's blocks are
> stored through Ceph. I have a total of 12 servers, so I'll end up with 1
> Controller node for openstack services and use the remaining nodes for
> ceph cluster and computing. 
>  Is it worth it to use a ceph storage system , and what would be the
> minimum number of nodes required to deploy it. 

Well, are we talking about serious production, or just playing?

Since you're talking about a single controller, without any sort of
redundancy, I am double-guessing that we're not talking about a serious
deployment here. If you were, I would strongly suggest that your Ceph is
made of:

- 3 ceph mon (that do not share any other role and do only that)
- at least 10 ceph OSD nodes, so that loosing one of them doesn't make
the full of your cluster super slow (as Ceph automatically would
rebalance the data to the 9 remaining nodes).

and also that your control plane is made of at least 3 nodes, and not
mix Ceph roles with anything else... This would be a serious deployment.

But since you seem super limited in therms of hardware, I would suggest
that you:

- Deploy 3 controllers on which you also install a Ceph MON
- Deploy Nova and Ceph OSD on the remaining 9 nodes.

This way, you still keep some kind of redundancy at least, if one of the
server fails. Remember: server do fail, it's a question of when, rather
than if. :)

I hope this helps,
Cheers,

Thomas Goirand (zigo)