[Mailman-Users] Load-balancing Mailman in LVS cluster

[Brad Knowles]

At 2:10 PM +1000 2004-06-29, Guy Waugh wrote:

>  I want to set up Mailman in a load-balanced fashion on two servers
>  running within an LVS (linux virtual server) cluster. I want the two
>  servers to act as the same Mailman instance.

	Okay, so far.

>                                                The two servers will mount
>  an NFS shared directory from a third server, and the NFS mount will, I
>  guess, contain the shared Mailman stuff.

	There's a problem.  NFS sucks at operations that require lots of 
file locking.  Of course, all queueing type operations involving mail 
servers involve lots of file locking.

	This is why you do not ever put /var/spool/mqueue on NFS, whereas 
you can find ways to kinda-semi-sorta deal with the NFS locking 
problem for user mailboxes on /var/spool/mail (all solutions to this 
problem involve trade-offs that hurt performance in other areas).

	Likewise, Mailman does file locking with the queueing process 
that it manages.


	If you can find a way to put things on a proper clustered 
filesystem, that should work much better.  Sistina GFS may work for 
you, or possibly Veritas VxFS plus their VCS tools.

>                                            I've found a few things on the
>  web about load-balancing Mailman, but not much.

	The thing is that you can run the web server for Mailman separate 
from the mail servers.  So, you could cluster the mail servers in a 
scalable way that will work for you, and then separately work on the 
issue of building a scalable web farm solution for the rest.

>  Further, is anyone running Mailman in a load-balanced fashion like this?
>  Any hints/tricks/tips?

	If you are interested in splitting of the mail cluster part of 
this equations, then I suggest you look at the parts of the FAQ that 
talk about performance tuning, especially the stuff in section 6. 
The most extensive entry is at 
<http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq06.003.htp>.

-- 
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

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