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

Les Mikesell lesmikesell at gmail.com
Thu Oct 25 02:28:23 UTC 2007

Christopher Chan wrote:
>>> 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?

Yes, I've had enough trouble with mysql that I'd look for any 
alternative, but to be far that was a few years back too.

>> 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?

I copied it from this email post.

>>>> 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?

zfs has the ability to make filesystem snapshots, then back them up with 
a send/receive operation.  See bottom of this page 
http://docs.sun.com/app/docs/doc/819-5461/ftyxi?a=view.  I haven't used 
it myself but it sounds handy.

   Les Mikesell
    lesmikesell at gmail.com

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