[Dovecot] Directory Layout Performance

[Seth Mattinen]

tomas at tuxteam.de wrote:
> On Wed, Jul 01, 2009 at 11:48:04AM -0700, Seth Mattinen wrote:
>> Mario Antonio Garcia wrote:
>>> From a performance perspective:
> 
> [...]
> 
>> I use a filesystem that handles this better than ext3 such as XFS or Reiser.
> 
> Ext3 should be fine for huge directories these days (given mount option
> dir_index it uses hashes for directory lists, but that should be the default
> in newer installations). You can find out whether it's on with "tune2fs <device>".
> 

Not sure about maildir, but I experienced horrible performance with ext3
on a very busy postfix queue a few years ago. The dir_index was on, it
was on a battery-backed hardware RAID, but it just couldn't handle it
until I reformatted /var to XFS in the middle of the day out of
desparation. Yeah, I know Reiser should have better performance with
lots of small files, but I had a scary reiser-ate-itself experience
once. As far as huge mbox files, XFS should have an advantage there.

I don't have any numbers beyond ext3 "mail is backed up, people are
complaining, and the load average is through the roof" vs. XFS "it's
easily keeping up with the queue, everyone is happy, and the load
average is sane". ;)

~Seth