[Dovecot] Dovecot write activity (mostly 1.1.x)

[mikkel at euro123.dk]

I’m experiencing write activity that’s somewhat different from my previous
qmail/courier-imap/Maildir setup.
This more outspoken in v.1.1.x than v1.0.x (I’m using Maildir).

Write activity is about half that of read activity when measuring throughput.
But when measuring operations it’s about 5-7 times as high (measured with
zpool iostat on ZFS).

I think this might be due to the many small updates to index and cache files.
Anyway since writing is much more demanding to the disk than reads
dovecots ends up being slower (only a little though) than my old
qmail/courier-imap/Maildir was. And the old setup didn’t even benefit from
indexes like Dovecot does.
(What I mean saying “slower” is that it can service fewer users before it
“hits the wall”).

Of course there’s also lot’s of benefits using Dovecot. I’m just wondering
whether this was a thing that should be focused on for later versions
(maybe writes could be grouped together or something like that).
Dovecot is very cheap on the CPU side so the only real limit in terms of
scalability is the storage.

Regards, Mikkel