On Sat, Aug 14, 2010 at 12:11 AM, Robert Hayden <rhayden.public@xxxxxxxxx> wrote:
Looking for guidelines on when RHCS components can be upgraded in a rolling fashion and when it is best to simply take a full cluster downtime. I am looking at 2-6 node clusters with each node providing a unique set of functions along with common functions. Each node has a dedicated failover node(s).
A couple of examples:
Minor OS upgrades, e.g. RHEL 5.3 to RHEL 5.5
Major OS upgrades, e.g. RHEL 5.x to RHEL 6.x
Errata for key cluster component, e.g. openais, cman, etc, without kernel updates
My understanding is that major upgrade require rebuilding the cluster from scratch, ie. no upgrade is possible. And with minor upgrades, I've tried doing rolling upgrades and sometime they do work and sometime don't. The problem is that you don't know which upgrades will work, so my current approach is just to upgrade the whole cluster at a time. Sure, requires some downtime (5-15 minutes) but that's better than having a freezed cluster requiring hours of work to get back online.
Just my $0.02.
Regards
Mikko
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