[CentOS] Large scale Postfix/Cyrus email system for 100,000+ users

Christopher Chan christopher at ias.com.hk
Thu Oct 25 01:58:35 UTC 2007

Les Mikesell wrote:
> Christopher Chan wrote:
>>>>> I thought the usual ways of doing this were to either use a 
>>>>> high-performance NFS server (netapp filer...) and maildir format so 
>>>>> you can run imap from any client facing server, or to keep the 
>>>>> delivery host information in an LDAP attribute that you find when 
>>>>> validating the address.
>>>> This is the 'I have the money' way of doing this ;-)
>>> There are at least 2 free ldap servers.  Or if you are stuck with 
>>> mysql you can probably add your own field for delivery host.
>> The service provider I used to work for tried openldap in 98. They got 
>> burned big time. Maybe it is up to the task today. What kind of 
>> hardware, though, would you use for one that the OP indicates will get 
>> a lot of writes? Everything I have read says LDAP is not for high 
>> write problems.
> 1998 was a long time ago.  Red Hat (fedora) directory server has claimed 
>  good performce for several years now.
> http://directory.fedoraproject.org/

Yeah, well, I guess the Fedora Directory server is unlikely to drop its 
entire datastore and will actually keep running but hey, are you going 
to migrate back to ldap if you have a system that is distributed across 
different mysql boxes running on cheap boxes and does its job?

> But the openldap guys think they are better - see page 33 of the pdf 
> linked from this page: 
> http://www.mail-archive.com/ldap@umich.edu/msg01151.html
> (22000 queries/sec, 4800 updates/sec on a terabyte database with 150 
> million entries - but I think the test box had 480Gigs of RAM...)

There you go. If you have the hardware, you can do openldap. 480Gigs? 
Did you add an extra zero?

>>> Does anyone have enough faith in a free NFS server to use it in this 
>>> scenaro these days?   How about opensolaris on top of zfs?
>> I would say. No comment on opensolaris in this scenario but I am happy 
>> with zfs as an offsite online backup solution.
> Are you using the incremental send/receive operation for this?

Huh? This is just rsync for the vpopmail maildir, user home directories, 
pervasive database files and scp for an Exchange backup file and then 
snapshotting on the zfs volume for the vpopmail and user home 
directories. Nothing heavy. What is this incremental send/receive 
operation that you are talking about?

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