choosing a file system

[Andrew Morgan]

On Tue, 30 Dec 2008, 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 also have a Dell/EMC SAN (currently a CX500 but upgrading to a CX4-240 
soon).  I'd like to dispel any rumors about SAN support though.  Dell will 
support pretty much any combination of software and hardware that has been 
validated by EMC.  This include RedHat, Suse, and Solaris that I'm aware 
of, plus more I'm sure.  Now, if you want to get support for the operating 
system itself from Dell, then you are probably limited to RedHat.  I know 
a lot of folks like to get their entire environment supported from a 
single vendor, but that can really limit your choices too.

We run Solaris 10 and Debian Linux with our CX500.  Dell helped us setup 
the Emulex HBA in the Solaris 10 boxes and connected it to the SAN. 
During the initial setup of the SAN, I installed Suse Enterprise on one of 
our servers so I could see what they did to install the Qlogic HBA and 
setup the SAN connection.  After they left, I blew it away and installed 
Debian Linux.  It's not "supported" by Dell/EMC, but this is all 
standardized hardware and software.  It works great with the 
kernel-included Qlogic drivers and even with standard linux multipathing.

> 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.

How did you determine that it was due to fragmentation?  We use ext3 here 
as well, so I'm curious.

> I'm looking for other solutions:
> ext4fs (does somebody use such filesystem?), xfs
> zfs (but we should switch to solaris or freebsd and throw away our costly
> SAN)

No need to throw away your SAN if you switch to another OS, see above.  :)

 	Andy