On 05/18/2016 01:15 AM, Ulrich Windl wrote: >>>> Ken Gaillot <kgail...@redhat.com> schrieb am 17.05.2016 um 16:53 in >>>> Nachricht > <573b3074.1040...@redhat.com>: >> On 05/17/2016 04:07 AM, Nikhil Utane wrote: >>> What I would like to understand is how much total shared memory >>> (approximately) would Pacemaker need so that accordingly I can define >>> the partition size. Currently it is 300 MB in our system. I recently ran >>> into insufficient shared memory issue because of improper clean-up. So >>> would like to understand how much Pacemaker would need for a 6-node >>> cluster so that accordingly I can increase it. >> >> I have no idea :-) > > A related question would be: What's in those segments? "strings" indicates > that there is a lot of XML in those segments, and I as programmer who's first > computer had 400 bytes of RAM wonder whether that is really needed... Aren't > there more efficient representations for information exchange?
That design choice was way before my time, so I can't speak to the reasons. I'm guessing it was an easy way to ensure compatibility across nodes with different OSes, software versions and machine endianness. >> >> I don't think there's any way to pre-calculate it. The libqb library is >> the part of the software stack that actually manages the shared memory, >> but it's used by everything -- corosync (including its cpg and >> votequorum components) and each pacemaker daemon. >> >> The size depends directly on the amount of communication activity in the >> cluster, which is only indirectly related to the number of >> nodes/resources/etc., the size of the CIB, etc. A cluster with nodes >> joining/leaving frequently and resources moving around a lot will use >> more shared memory than a cluster of the same size that's quiet. Cluster >> options such as cluster-recheck-interval would also matter. >> >> Practically, I think all you can do is simulate expected cluster >> configurations and loads, and see what it comes out to be. > [...] > > > Regards, > Ulrich > > _______________________________________________ Users mailing list: Users@clusterlabs.org http://clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org
