[Cialug] March == Zimbra

[Daniel A. Ramaley]

On Thursday February 5 2009 22:42, Josh More wrote:
>There has been some interest in having a meeting about Enterprise Open
>Source email solutions, so I'm altering the schedule somewhat.  In
>March, the meeting topic has been changed to be about Zimbra.  If you
>are interested in helping with the presentation, please reply to this
>email.  I know of one person who has committed, but he'd like some
> help.

I'm involved with Zimbra at Drake. We have about 8 or 9 thousand 
accounts. I'd consider attending the March meeting even though 
Wednesday is the one weekday evening when i have other commitments. 
However, for the March meeting i'll be in Hawaii. Coincidentally, once 
the time zones are factored in, right about the time the meeting starts 
is when my wedding starts. So, i probably won't be thinking much about 
either Zimbra or Linux. Sorry.

Some things i can say about Zimbra though:

It works. Very well. For a small organization, it could easily act as 
the master directory service in addition to doing e-mail, calendaring, 
instant messaging, and everything else Zimbra does. Here we have a 
legacy LDAP service that everything authenticates to, so rather than 
have Zimbra be authoritative we configured it to authenticate off of 
the existing LDAP. That configuration is supported and works well.

If you go with the network (paid) edition, take Zimbra's memory 
recommendations and double them. RAM is cheap, but downtime caused by 
memory exhaustion is not (especially when it is the weekend and you'd 
rather be doing something else). Zimbra makes heavy use of java. Not 
having programmed in that language, i'm not sure if java is inherently 
leaky in its handling of memory, but Zimbra likes its RAM. Version 
5.0.8 had some rather nasty leaks, but since upgrading to a newer 
version some of the memory issues have gone away.

Do not put your mailstores on a slow NAS with a GFS2 filesystem. It 
sounded like a good idea at the time, but it is horrendously slow. 
Deleting 1 days worth of backups takes 3 hours. And the daily backup, 
frustratingly, takes more than a day. As soon as we can find the money 
for a faster disk arrangement, we're migrating to that and probably 
switching to the ext3 filesystem. I just shudder to think how long mail 
will be down if fsck needs to run against 2 terabytes of storage. Even 
if it is split up into multiple partitions, that's still going to take 
awhile. In the mean time i hope no one needs something restored from 
backup...

If someone is setting up a large-ish installation i could probably give 
some recommendations about hardware to buy. We have a total of 7 
servers. 2 are redundant LDAP servers, 2 are redundant MTA servers, and 
the remaining 3 act as a cluster (with 2 active and 1 failover nodes) 
for the mail stores. Except for differing amounts of RAM, the machines 
are almost identical. But if i were setting Zimbra up again, i'd use 
the LDAP servers for something else and get slower machines to replace 
them. Or maybe run the LDAPs virtualized on the same hardware they are 
on now but in concert with some other VMs. Basically the LDAP servers 
don't need to be as powerful. The MTAs are a bit underutilized as well. 
It is really just the mailstores that need a lot of horsepower. For 
small installations with just 1 Zimbra server, well, i guess i'd say 
just make sure it has a couple CPUs (or cores) and plenty of RAM.

For a better idea of hardware, our 2 LDAP servers have 8 GB RAM, of 
which about 1/2 GB is actually used. 1 GB would probably be adequate 
once caching is considered. The MTAs each have 16 GB, of which 2-3 GB 
seems to be in use. The mailstores have 24 GB, of which 8 GB is in use 
now. With a slightly older version of Zimbra we'd often see 20 or 22 GB 
in use (after running for about a week). Usually at around 22 GB Zimbra 
would wedge so hard it couldn't be restarted through software and the 
machine would have to be power cycled. All these machines have dual 
quad core CPUs (8 cores total), but the LDAPs and MTAs could easily get 
by with 2 cores. It is really just the mailstores that see much load.

If anyone has any specific questions about running Zimbra, let me know.

------------------------------------------------------------------------
Dan Ramaley                            Dial Center 118, Drake University
Network Programmer/Analyst             2407 Carpenter Ave
+1 515 271-4540                        Des Moines IA 50311 USA