flat mailboxes performances for around 1500 entries

[Stephen L. Ulmer]

On 1 Sep 2005, dgm+ at pitt.edu said:
> Patrice wrote:
>
>> Does someone know if the flat format type  for my
>> /var/imap/mailboxes.db is good enough for only 1500 mailboxes ?
>
> We use flat in our setup.  We have about 65000 users with 264265
> mailboxes.
>

We were using flat for about that size (65000, though we used it at
1500 too).

>> or it will impact performances ?
>
> It works fine for us.  Whether other formats would perform better, I
> can't say.  We never benchmarked.  Flat format isn't as bad as you
> would initially think, since cyrus mmap()s the file anyway.  The big
> hit you take is that each update requires the entire file to be
> re-written.

Somewhere way back we switched to skiplist, and we are EXTREMELY happy
with it. I'm confident that we have enough activity now that just the
mailbox.db updates from folder creates would cause significant delays
while the file was re-written.

I don't know if Dave is running a murder, but it seems to us that
mailboxes.db updates on the proxies just work better with skiplist.

Good luck,

-- 
Stephen L. Ulmer                                      ulmer at cns.ufl.edu
Senior Systems Programmer                         http://www.ulmer.org/
Computing and Networking Services                   VOX: (352) 392-2061
University of Florida                               FAX: (352) 392-9440
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