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Re: Sugesstions building a rather big mail system.

Am Mon, 2003-10-06 um 16.03 schrieb Fredrik:
> Hello fellow sysadmins, 
> I have been aproached about building a rather big mail system handling
> 500.0000 existing accounts (running today on a windows based product (ick))
> with a growth about 50.000 new accounts per year.
> The services needed is: smtp, pop3, imap4. 

As mentioned before: Sounds like fun! :-)

I recently build a similar mail-cluster with OSS only. Tough it's
currently smaller (20k user) it was designed to grow as needed. I guess
it could handle 500k user without any modification except additional

> I have used LVS for about 3y with good results for 30.000 acounts. 
> But this is certainly a bigger project. Should I go for alteon or any other
> closed product or stick with LVS?

I don't see any need for something other than LVS, especially not for a
mail-cluster. If you have any doubts about the throughput of your
a) Use Gbit interfaces and direct-routing
if that's not enough (tough I doubt it)
b) Use multiple MX records, each pointing to a separate set of balancers

> My main concern is the storage. SAN? 

Well, I guess that's the only "problem" you'll have.
Either you use some BIG SAN or NAS (NetApp, EMC) or you use your
software to distribute it across multiple server.
I did the later as it's probably much cheaper (haven't calculated for
500k user, just for 20k to 100k). Here's how:

The MX server run Postfix with a MySQL backend for authentication (and
spam-filtering, virus-scanning, server based filter, ...). Depending on
the users maildir they access different server via NFS to store their
Mail. Each of those is equipped with about 1TB disks to store the mails.
The POP/IMAP server do the same thing vice versa.

Real fun is backing up the data as you have lots of small files across
multiple servers which are changing all the time as users access their
mail via IMAP or receive something. For 500k user you'll probably want a
quite good backup concept too. Using a SAN or NAS approach for storage
might be an advantage here.

> Anyone used supersparrow for source based load balancing?
Nope. Don't see a reason why to use it here as LVS does everything (and
more) I need for setting up something like this.

As hardware planning might go "a little" in detail (and therefore become
OT), feel free to contact me off-list.

best regards,
Markus Oswald <moswald@iirc.at>  \ Unix and Network Administration
Graz, AUSTRIA                     \ High Availability / Cluster
Mobile: +43 676 6485415            \ System Consulting
Fax:    +43 316 428896              \ Web Development

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