Implement Cyrus IMAPD in High Load Enviromment

[Lucas Zinato Carraro]

Hi, I am deploing cyrus-imapd in my organization:

My organization need to have:

 - 75000  maiboxes
 - 10000 simultaneous connections (IMAP)
 - 3000 mailboxes with 1Gb and 65000 with 200Mb
 - 12 Tb for spool ( EMC Clarion Storage )
 - 15 servers with Xeon 2.6ghz - 8gb RAM
 - GNU/Linux 2.6 for Operating System ( RedHat, Debian etc ... )
 - ~ 150000 messages / day
 - Postfix as MTA

I made several tests  to choose filesystem.
 Cluster FS( gfs, ocfs ),  ext3, ext4 , reiserfs , xfs and etc..
my choice

ext3  with   dir_index, noatime, nodiratime

and partition my  problem with Cyrus Murder.

My doubts are:

- Exist a recommended number of conections to a front end server ?
( a parameter in sysctl.conf in GNU/Linux )

- Exist a recommended size to a Backend server ( Ex: 1 Tb )?

Cyrus IMAP works great with large mailboxes an billions of small files.
Backup is my big problem.

- Exist any solution better than make a SNAPSHOT of STORAGE and backup all
file system (/dev/sdaX ) ?

I know that performance is  terrible with billions of small files, and make
tests using tar . (  ex: a.tar.gz = /var/spool/imap/a/ ), this approach
increase the performance with my LTO tapes.

Anyone has another suggestion  ?


Regards,
Lucas Zinato Carraro
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