[Mailman-Users] Load-balancing mailman between two servers

[Brad Knowles]

At 10:08 AM +1100 11/29/06, Guy Waugh wrote:

>  I'm still wondering whether I should be NFS-sharing the qfiles
>  directory. I haven't delved into the Mailman source code to try to
>  figure this out, but...

In theory, it should work.  I wouldn't do it myself, because of the 
contention and locking issues, but it should work.

>  If, for example, a list post is held for (say) moderation in one
>  server's qfiles directory (if this is in fact where held posts are
>  kept?), and a list administrator accesses the Mailman web interface on
>  the other server and approves the post, will the second (web interface)
>  server be able to find the held post on the first server? I can't
>  imagine that it would be able to find the post, if it is the case that
>  posts held for moderation (and for other reasons, like posts by
>  non-members to a member-only list etc. etc.) are held in the qfiles
>  directory.

I believe that you are correct -- if the post is held on only one 
server, and you happen to log into the other server to approve the 
post, then the second machine would not see that post to approve it.

>  Maybe I should change my setup like you outline above, such that the
>  *entire* Mailman installation is NFS-shared between both servers?

My understanding is that it should work, modula the additional 
problems caused by putting things like shared queues on NFS (e.g., 
file contention, locking, etc...).

>  The
>  only anomaly to be dealt with here, AFAIK, is that Mailman writes a
>  master-qrunner.pid file to the data directory, but I can get around
>  that. I'd really prefer to leave it roughly the way I already have it,
>  as I can upgrade Mailman on one server and test it while the old version
>  is still running on the other server.

To be honest, I've never done it myself, and we don't use it on 
python.org (the home of the mailman-* lists).

So, I can't tell you how well it will or will not work, or what the 
precise little quirks will be.  I can tell you about the typical 
types of issues that I know about in general with NFS, and how I 
would expect those to apply with this type of usage.

That said, I believe that there are some people on the list who are 
doing this sort of thing (I mean, this topic has come up a few times 
before), and I believe that most of them are doing the simple thing 
of just sharing the entire /usr/local/mailman/ hierarchy between the 
target systems.

-- 
Brad Knowles, <brad at shub-internet.org>

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