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Re: POP3 and SMTP server for an ISP

On Friday 23 February 2001 10:02, Roger Abrahamsson wrote:
> I've been closely following this thread, and I was wondering what sort of
> system that would be recommendable for 50.000+ users? No local access and
> no home directories is wanted, but pure mass hosting. Maildirs I assume is
> essential.
> I've tried some programs, but they fail horribly when the system gets
> big. I have been wondering about file system limitations too. Say you have
> 5000 users in each subtree and they have between 100 and 30.000 emails in
> their folders. (The large figure is an example of a smartass like me. lol)
> Preferrable all user authentication is done in MySQL or other SQL server.

If you use Ext2 then you need multiple file systems, otherwise fsck times 
will be ridiculous.
ReiserFS will perform best for this and journalling avoids fsck times, but 
the fsck program isn't as capable as we would like yet.

Ext3 only works on 2.2.x kernels and is quite beta.

Postfix should work if you use something like maildrop for delivery.  
Apparently you can hack wrapper scripts to check LDAP or SQL for user 
details.  I'm investigating this myself now.

With 50K users if they have an average mailbox size of 5M you'll need 250G of 
storage.  You may gain from having multiple file systems on different 
hardware devices.  EG you could have two RAID-10 arrays each containing 4*72G 
drives for 144G of mirrored storage each (total 300G should be enough).  Then 
if you have to FSCK them you can do it in parallel.  Also having two separate 
file systems should speed up delivery on SMP machines (haven't tested this 
theory though).

http://www.coker.com.au/bonnie++/     Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/       Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/     My home page

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