Am 06.12.2013 11:32, schrieb JEHERUL: > Currently we are running a mail system for 10000 users each 2GB mailbox. At > present we have 5 mail servers where > users mailboxes are distributed almost uniformly. We have a HP SAN Storage > (HP EVA 6400) where mailboxes are > stored. We partition the storage into five vg and each is mounted on the 5 > servers. We are using postfix and dovecot. > > The system was running fine but currently we notices high IO load due to > IMAP connection. So we are planning to > build a dovecot cluster. > > Please suggest some design for the dovecot cluster keeping in mind to our > scenario. (If needed we can buy > additional hardware like load balancer)
this belongs to the dovecot-list however, maybe look at the dovecot proxy feature http://wiki2.dovecot.org/PasswordDatabase/ExtraFields/Proxy you could split the userbase to different machines while the connection happens always on the proxy which can with a sql-database containing the target server spread the load, this way the dovecot-proxy would be the load-balancer and I/O no longer on one machine but as you say "HP SAN Storage" which is typically used as shared storage avoid using the same storage backend for the other machines on the other hand: consider look for a enclosure to add more disks to the SAN storage the more disks the spindle has the more IOPS/performance at least for the HP MSA series are enclosures available for 12 additional disks on the same controller
