[Linux-HA] MMM conflict with Pacemaker
marcus at synchromedia.co.uk
Thu Feb 16 02:17:32 MST 2012
I have 5 servers where 2 are running a redundant web front-end with pacemaker (managing a single floating IP), two are running MySQL with mmm agents and the last one is running the mmm monitor node. So at present there is no overlap between these groups. I need to retire one of the web servers and its functions will be moved to the machine currently doing mmm monitoring. Easier said than done.
If I install pacemaker (from the linux-ha PPA for Lucid, with empty initial config, as per the docs) and start its corosync service, mmm's monitor goes nuts, loses connectivity to agents causes them to drops their floating IP (even though it's not on the machines involved with pacemaker). I can appreciate that there is some overlap in functionality, but I don't see why it should conflict like this. Anyone got an explanation? Is anyone else running this combo?
I've temporarily bypassed the front-end so I can work on this, so I'm clear to start entirely from scratch. This is proving difficult too, since the shifting terminology means documentation is mostly out of sync - of the three guides I've tried so far, one doesn't mention ha.cf at all (others do, but with obsolete options), one suggests doing everything with corosync (though appears to be missing any config for pacemaker). One thing that would be very helpful is something to explain the relative merits of ucast, bcast and mcast options, as I suspect they may be part of the problem I'm seeing with mmm.
(and I'm not looking to switch to DRBD!)
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