Re: ext2/3 files per directory limits

[Andrew Morton <akpm@osdl.org>]

Ron Peterson <rpeterso@mtholyoke.edu> wrote:
>
> I would like to better understand ext2/3's performance characteristics.
> 
> I'm specifically interested in how ext2/3 will handle a /var/spool/mail
> directory w/ ~6000 mbox format inboxes, handling approx 1GB delivered as
> 75,000 messages daily.  Virtually all access is via imap, w/ approx
> ~1000 imapd processes running during peak load.  Local delivery is via
> procmail, which by default uses both kernel-supported locking calls and
> .lock files.
> 
> I understand that various tuning parameters will have an impact,
> e.g. putting the journal on a separate device, setting the noatime mount
> option, etc.  I also understand that there are other mailbox formats and
> other strategies for locating mail spools (e.g. in user's home
> directories).
> 
> I'm interested in people's thoughts on these issues, but I'm mostly
> interested in whether or not the scenario I described falls within
> ext2/3's designed capabilities.
> 

noatime will help.

increasing the journal size _may_ help.

With 6k files per directory you'll benefit from indexed directories
(htree).  Use `tune2fs -O dir_index'.  dir_index isn't available for ext2.