On Tuesday, September 4 at 12:16 PM, quoth Ken A:
I'm switching from a pop3 only dovecot install to a pop3/imap install and I'm wondering how many connections every 100 'normal' imap users might have/keep open?
Mmmm, I usually estimate that most of the time users keep one connection open. Occasionally some clients (like Mail.app with the IDLE plugin) keep two or three open at all times. Then of course, there's occasional bursts where a client may open ten or more connections, though because IMAP is asynchronous that's technically unnecessary unless you're doing it to reduce latency (unlikely), but some clients do it anyway.
So I'd leave a max of around 300-500 connections at minimum.
I'm wondering if I need to tweak any o/s related things, like time_wait, etc. Any pointers would be greatly appreciated.
The thing to keep in mind about IMAP versus POP is that more folks will be keeping things on your server. That means you're going to need more disk space and (particularly if you use a Maildir backend) more inodes, and you're going to want to reexamine your filesystem and mount options. For example, if you haven't already, turn off atime updating. It's entirely useless with Dovecot, and will just slow you down.
~Kyle
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