Hi Guys,
I've been desperately trying to find some comparative performance information about the different mailbox formats supported by Dovecot in order to make an assessment on which format is right for our environment.
This is a brand new build, with customer mailboxes to be migrated in over the course of 3-4 months.
Some details on our new environment:
Approximately 1.6M+ mailboxes once all legacy systems are combined
NetApp FAS6280 storage w/ 120TB usable for mail storage, 1TB of FlashCache in each controller
All mail storage presented via NFS over 10Gbps Ethernet (Jumbo Frames)
Postfix will feed new email to Dovecot via LMTP
Dovecot servers have been split based on their role
Dovecot LDA Servers (running LMTP protocol)
Dovecot POP/IMAP servers (running POP/IMAP protocols)
LDA & POP/IMAP servers are segmented into geographically split groups (so no server sees every single mailbox)
Nginx proxy used to terminate customer connections, connections are redirected to the appropriate geographic servers
Apache Lucene indexes will be used to accelerate IMAP search for users
Our closest current live configuration (Qmail SMTP, Courier IMAP, Maildir) has 600K mailboxes and pushes ~ 35,000 NFS operations per second at peak
Some of the things I would like to know:
Are we likely to see a reduction in IOPS/User by using Maildir alone under Dovecot?
What kind of IOPS/User reduction could we expect to see under mdbox?
If someone can give some technical reasoning behind why mdbox does less IOPS than Maildir?
I understand some of the reasons for the mdbox IOPS question, but I need some more information so we can discuss internally and make a decision as to whether we're comfortable going with mdbox from day one. We're very familiar with Maidlir, and there's just some uneasiness internally around going to a new mail storage format.
Thanks!