I do this with a custom monitoring script (I don't use the standard Hobbit 'procs' test).
There should be something you can check via script that tells you if a server is primary or not. In my case, a database filesystem is mounting on the primary but not on the secondary. So my script uses 'df' to look for that filesystem. You could use 'mount' as well. If that database filesystem is mounted the script does the normal test for processes and reports red/green. But if it's not mounted, the script reports a clear condition.
-----Original Message----- From: Charles Jones [mailto:jonescr at cisco.com] Sent: Friday, September 21, 2007 1:12 PM To: hobbit at hswn.dk Subject: [hobbit] Advice on how to handle HA monitoring
We have 2 hosts, HostA and HostB. They are part of an HA cluster via HP ServiceGuard. There is a virtual IP and DNS name of "virtual" that automatically goes to whichever of HostA and HostB is the primary at the time.
I am currently monitoring both HostA and HostB via Hobbit. Currently HostA is the primary, and I am doing various PROC checks. Currently on HostB, I am not doing process checks.
My problem is, how do I smoothly handle a failover scenario (HostB becoming the primary)? When a failover occurs, all of the procs on HostA are stopped (either by the server crashing, or manualy by ServiceGuard), and the same procs are started up on HostB.
I'm trying to think of ways to monitor both hosts, but only monitor procs on the one that is primary. So far the best I can come up with is to run the hobbit clients in local mode, and maybe have the ServiceGuard scripts swap out the config files and restart the Hobbit clients when there is a failover. That would probably work, BUT in this case the Hobbit homdir is also the same (SAN mount) on both machines, so moving or editing a file on one does the same on the other :(
Simply shutting down the hobbit client on the non-primary is not an option, as then it would no longer be monitored at all.
Any ideas? :)
-Charles
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