[Dovecot] Calculation of suggested vsz_limit values

[Timo Sirainen]

On Mon, 2011-12-19 at 22:45 -0800, Robin wrote:
> Timo <tss at iki.fi> wrote:
> 
> > Not really. For mail related processes (imap, pop3, lmtp) you could
> > find the largest dovecot.index.cache file and make sure that
> > vsz_limit is at least 3 times that.
> 
> Yikes.  Aside from forcing users to "prune" mailboxes, what do you 
> suggest when vsz_limit exceeds available host RAM?

vsz_limit isn't about actually using that much memory, but about how
much address space can be allocated. Just because Dovecot mmap()s a 1 GB
dovecot.index.cache file doesn't mean that it physically uses more than
a few kilobytes of memory.

> I ran across another "RAM only" process in fts_squat for a large, but 
> not *HUGE* mailbox when the size of the dovecot.index.search.uids file 
> got larger than 600MB.

I suggest switching to fts-lucene in Dovecot v2.1.