Hi Marcus,

One Issue I can think of is, Pacemaker wants to bind the floating IP as eth#:#, 
while MMM wants to use a different method that can only be seen with the IP 
command.   I think they are fighting over who owns the floating IP.

Have you read my full HOWTO at 
http://www.mysqlfanboy.com/2012/02/the-full-monty-version-2-3/ ?

Yes HA systems are very confusing.   Pacemaker is the name of an older 
application.  Corasync is it's new name but some of the files still maintain 
the old name. 

You should know, even the developer of MMM has abandoned it.  The author of MMM 
(Alexey Kovyrin) said in a reply to Brian his blog “…Every time I try to add HA 
to my clusters I remember MMM and want to stab myself because I simply could 
not trust my data to the tool…”.  Read 
(http://www.xaprb.com/blog/2011/05/04/whats-wrong-with-mmm/) 

Pacemaker is the way to go. But, yes, it is difficult.  I hope my HOWTO helps.


----- Original Message -----
From: "Marcus Bointon" <[email protected]>
To: [email protected]
Sent: Thursday, February 16, 2012 3:17:32 AM
Subject: [Linux-HA] MMM conflict with Pacemaker

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!)

Marcus
-- 
Marcus Bointon
Synchromedia Limited: Creators of http://www.smartmessages.net/
UK info@hand CRM solutions
[email protected] | http://www.synchromedia.co.uk/



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