[ClusterLabs] Maximum number of nodes support in single cluster

[Ken Gaillot]

On Fri, 2019-11-22 at 07:32 +0000, S Sathish S wrote:
> Hi Team,
>  
> In Clusterlab below pacemaker and corosync version what is maximum
> cluster nodes its supported ? will it support for 120 nodes in single
> cluster?
>  
> corosync-2.4.4 à  https://github.com/corosync/corosync/tree/v2.4.4
> pacemaker-2.0.2 à 
> https://github.com/ClusterLabs/pacemaker/tree/Pacemaker-2.0.2
>  
> if we have 120 nodes in single cluster let us know if any impact or
> consideration need to take for any cluster configuration parameter ,
> please suggest.
>  
> let us know if any recommendation of cluster nodes limit pre-defined.
>  
> Thanks and Regards,
> S Sathish

At this time, nowhere near 120 full cluster nodes are supported.
There's no official limit by the upstream projects, because so much
depends on hardware and applications, but commercial entities often
limit support to 16 or 32 nodes. Going above 16 will likely require
high-end hardware and careful tuning of corosync parameters.

However pacemaker does support lightweight nodes via Pacemaker Remote:

https://clusterlabs.org/pacemaker/doc/en-US/Pacemaker/2.0/html-single/Pacemaker_Remote/

The scalability of Pacemaker Remote isn't well known. Some users have
reported problems with as few as 40 remote nodes, while others have
gotten above 100 without problems.
-- 
Ken Gaillot <kgaillot at redhat.com>