[Dovecot] Recommended FS for Dovecot Maildir

[Fran Fabrizio]

> I've heard that for Dovecot/Mailir systems there are filesystems that 
> are optimised for the situation of many small files in one folder.
>
> Could I possibly have some feedback on what the recommended 
> filesystems are? I've heard of ReiserFS but was wondering what other 
> options there are and how they compare.
I happen to also be investigating this, and I too keep hearing the 
Reiser is the way to go for Maildirs.  However, when I went looking for 
benchmarks to support this, the information out there is sparse, 
confusing and contradicting.  For instance, here's a benchmark showing 
Reiser being among the slowest filesystems in many areas...  
http://linuxgazette.net/122/piszcz.html

Here's a guy who claims that Maildir + ReiserFS is a win but then when 
you look at his numbers it appears that Reiser was slower than ext3...   
http://www.decisionsoft.com/pdw/mailbench.html

This guy has Reiser as the slowest...  
http://www.thesmbexchange.com/eng/qmail_fs_benchmark.html

And so on.  You can find benchmarks that show Reiser as the best, ext3 
as the best, xfs as the best, jfs as the best.  All for maildirs.  So, 
I'm not sure if I can trust any of the benchmarks.

One thing that seemed consistent is that everyone had xfs performing 
pretty well.  I am configuring a new RAID array for my Maildirs and so I 
am in a position where I can test various filesystems now.  I tried xfs 
on Fedora Core 5 and it crashed the kernel, so that was a bummer.  As 
soon as I did the mkfs -t xfs and rebooted, system hangs during startup 
right when it is looking at the disk array to find the filesystems.  I 
am probably going to go to suse enterprise linux or redhat enterprise 
linux for this server and see if stability is there, but I'm really 
starting to lean towards the "ext3 because it works good enough" camp, 
and optimize elsewhere.  More disks in the array, more memory in the 
servers, etc...

-Fran







-- 
Fran Fabrizio
Senior Systems Analyst
Department of Computer and Information Sciences
University of Alabama at Birmingham
http://www.cis.uab.edu/
205.934.0653