Re: Two Questions: Division of Labor and NFS issues

John Madden wrote the following on 04.03.2005 04:58 :

>>I've been thinking about this very issue. I always felt that Postfix
>>with Amavisd-New (Spam/Virus scanning) was working great. The CPU is
>>definately being used but its in no way over-burdened. The only thing
>>killing us is IO and that is a direct result of NFS and mbox. You have
>>helped make my decision easier. I'm going to prepare to make the
>>conversion from mbox to maildir format. That should be all I need to do
>>to solve our critical issues.
>>
>>
>
>Be sure to consider your choice of filesystem carefully, if you haven't
>thought of that yet. The downside of maildir is the number of files you have
>to deal with and older filesystems don't handle that scenario very well.
>Avoid UFS, ext?, etc., and shoot for veritas, reiserfs, etc.
>
>

ext3 with recent kernels (at least for one year, maybe more) supports
b-trees to speed up these cases:
mke2fs -j -O dir_index <your_device>

It should bring it in the reiserfs range but I didn't benchmark this.

Note: the number of files per dir is mainly a problem if the clients
leave their messages on the server.
Note2: if you have a high number of mailboxes (say tens of thousands) in
the same directory, the problem comes back (you can implement
"virtual/domain/u/s/user" schemes though).

Lionel.