[Mailman-Users] Synchronizing Mailman between two servers.

Brad Knowles brad at stop.mail-abuse.org
Thu Sep 22 19:02:21 CEST 2005

At 9:46 AM -0500 2005-09-22, Brian Elliott Finley wrote:

>  I'm very interested in the solution you chose, and in how well it works
>  for you.

	Sorry, I missed the original message.

>  I'm in the process of designing a fault-tolerant mailman installation,
>  and any wisdom from experience would be very useful.

	Generally speaking, I don't think that many people try to do 
this.  You can off-load the web processing with multiple front-end 
web proxies, and you can off-load the mail processing with multiple 
inbound and outbound mail servers (usually best kept as separate 
groups, since the anti-spam, anti-virus, and certain other 
requirements are different for inbound versus outbound use), and the 
rest is just Mailman itself.

	But, if you do want to go the whole nine yards, the Mailman 
programmers have been pretty careful to keep everything relatively 
NFS-safe, so you should just be able to have an NFS filesystem which 
is then mounted on all of the Mailman servers (preferably served by a 
high availability/redundant NFS server cluster).  Doing things over 
NFS will slow down individual operations, but the overall aggregate 
throughput might be able to be higher, if the NFS server has the 
right architecture and you spread the load out across enough Mailman 
servers, etc....

>>  Any thoughts on what is the best way to synchronize mailman databases
>>  between to linux boxes?

	Mailman doesn't really use databases.  At least, not 
out-of-the-box.  There are third-party unsupported patches to allow 
database member adapters, but that's about it.

	Mailman stores pretty much everything into Python "pickle" files, 
which is a particular binary Python-specific file format that can be 
quickly saved and re-loaded in the native binary format.

>>  If my alias_maps are defined the same in /etc/postfix/main.cf are the
>>  same on both hosts can I just duplicate my /usr/lib/mailman and
>>  /var/lib/mailman directories?

	Duplicate?  What do you mean by "duplicate"?  Just once?  If so, 
then the directories would get out-of-sync.  You'd have to keep all 
the directories in sync somehow.

	In a nearline backup method, something as simple as rsync would 
suffice, and would potentially only lose any information that was 
written since the last rsync.

	In a production OLTP type of environment, you'd have to use 
shared filesystems between the sets of machines, and you'd have to 
make sure that those shared filesystems implement all the necessary 
cluster-wide locking facilities, etc... to keep Mailman working 

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.

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