[Mailman-Users] Synchronizing Mailman between two servers.

[Brad Knowles]

At 11:46 AM -0600 2005-09-22, Ivan Fetch wrote:

>     i'm looking at this for our setup as well.  How are others handling
>  the Mailman processes (qrunners) starting on a second server once the
>  first server has gone down, and switching back to the first server once
>  it has recovered?

	You'd have to have some sort of "heartbeat" monitor application 
which uses the standard OS start/stop routines when it decides that 
the other system has gone down, and might need to put in some 
additional lock cleanup code in there.

	Moreover, you'd have to make sure that the problem is not in the 
heartbeat monitor script, which could potentially cause the Mailman 
processes on both machines to be running and each think that the 
other is down.  You'd also need to make sure that you don't start 
Mailman on the second machine if the shared filesystem is not 
properly available.  And there are a bazillion other potential 
failure modes that you'd also need to look out for.

	Doing high availability is tough.  Much tougher than anyone ever 
gives it credit for.


	The problem is that Mailman was never designed to be used/abused 
in this way, so you're pretty much in completely uncharted water.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.