[Dovecot] Migration questions...

[Richard Hobbs]

Seth Mattinen wrote:
> Phillip Macey wrote:
>> On 14/05/2009 5:11 PM, Steffen Kaiser wrote:
>>> On Wed, 13 May 2009, Richard Hobbs wrote:
>>>> The main complaint we have from users is that their IMAP Inbox, with
>>>> 5000 emails in it takes ages to appear, and no amount of coaxing will
>>>> convince them to split their inbox into multiple folders.
>>> Oh, we serve Maildir via Dovecot IMAP and 5000 messages per folder are
>>> a wimp. Problems start if the user:
>> We are having some performancec issues on our server at the moment - all
>> I can put it down to is the large size of some maildirs. Eg. `ls -ld
>> Maildir/cur` might show a directory >20Mb in size for some of our users
>> (20-30k emails).
>> (Performance issues == everything is running ok then all of a sudden
>> load avg goes through the roof, system cpu time goes crazy. Reading mail
>> grinds to a halt. Then everything recovers just as suddenly and the load
>> avg gradually returns to normal levels)
> 
> Are you using ext3 by chance? Vanilla ext3 without directory indexing
> (or whatever it's called) *hates* directories with a lot of files - like
> maildir. Personally, I use XFS, which doesn't suffer from this problem
> since it uses b-trees instead of a table(!) like ext3 does.

This raises another question for me actually...

We will have one volume for indexes and another volume for data (using
maildir). We will be using the latest stable Debian Linux distro.

Any opinions on the best filesystem to use? We would normally go
ReiserFS for large volumes, and ext3 for small volumes because of the
unlimited inodes in reiserfs, but i understand that support for that is
beginning to disappear given that Hans Reiser got into a bit of trouble
a few years ago.

Anyway... that would leave ext3, but is there a better choice i could
make in this instance? We do want performance, of course, but also
complete reliability and resilience when it comes to system crashes
etc... we do *not* want data corruption, and ext3 we know has a very
good journalling and data recovery methods. Well... they're very mature,
anyway.

Any opinions?

Thanks again!

Richard.

-- 
Richard Hobbs (IT Specialist)
Toshiba Research Europe Ltd. - Cambridge Research Laboratory
Email: richard.hobbs at crl.toshiba.co.uk
Web: http://www.toshiba-europe.com/research/
Tel: +44 1223 436999        Mobile: +44 7811 803377
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