choosing a file system

[Shawn Nock]

LALOT Dominique wrote:
> Hello,
> 
> We are using cyrus-imap for a long time. Our architecture is a SAN from EMC
> and thanks to our "DELL support" we are obliged to install redhat. The only
> option we have is to use ext3fs on rather old kernels. We have 4000 accounts
> for staff and 20000 for students
> The system is rather fast and reliable. BUT..
> 

We support ~8000 faculty and staff and ~45000 students. On 16x 250G
reiserfs 'partitions' from and EMC CX500 arrays. Reiserfs has proven to
handle the load much better than ext3 (which we tested... it was a
disaster). We've been using reiserfs since RedHat Linux 7.x. We also
tested an early xfs patchset... but it was prone to corruption (but that
was years ago).

> Once, there was a bad shutdown corrupting ext3fs and we spent 6 hours on an
> fsck.
> Next we discovered that our backup system was going slower and slower. We
> just pointed out that it was due to fragmentation, and guess what, there's
> no online defrag tool for ext3.

We've only had to reiserfsck a partition once (with --rebuild-tree
eek!). It took a while, but the data was intact... it beats restoring
from tape.

We don't defragment (as such). In an attempt to speed up overnight
backups we once did a scripted rename of mailboxes to spare partitions.
Since this time we have given up on filesystem based backup and simply
do a block-level backup in combination with partition snapshots. Keeping
the cyrus partition size low has limited many of our problems and we do
a scripted rename of mailboxes to balance partition utilization when we
add another partition.

Bron and the fastmail guys could tell you more about reiserfs... we've
used RH&SuSE/reiserfs/EMC for quite a while and we are very happy.

Except those loony folks who want Exchange...

Shawn
-- 
Shawn Nock (OpenPGP: 0xFF7D08A3)
Unix Systems Group; UITS
University of Arizona
nock at email.arizona.edu

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