[ClusterLabs] Maximum number of nodes support in single cluster

[Jan Friesse]

Ken Gaillot napsal(a):
> 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.

Actually we were testing successfully 59 nodes with corosync 2 and no 
"careful tuning" of corosync parameters was needed. Corosync 3 control 
messages size was reduced significantly, so results should be even better.

No matter what, more than 32 fully synced nodes seems to be asking for 
the problems and pcmk remote seems like a better choice.

Regards,
   Honza


> 
> 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.
>