Hi,

On Tue, 17 Feb 2009, Bob Barton wrote:

> Hi All
> I am setting up a 2 TB file system to use for AFS volumes on an AFS file 
> server and I am wondering which file system I should use - XFS or ext3. I 
> plan to use Scientific Linux 5.1 or 5.2 x86_64 as the operating system on the 
> file server machine.
> Suggestions, comments and recommendations are very welcome.

we're running a not-so-small AFS cell on SL5.2 x86_64 servers. All vice
partitions are ext3, we've never had to regret this choice, and have no 
plans to use xfs instead.

We also run a not-so-small amount of non-AFS storage - using xfs, because 
for that application it does have significant advantages over ext3.

Whatever filesystem you choose, make sure you get the rest of your setup 
right, it will have much more impact on your fileserver performance. In 
particular:

- Choose the right set of fileserver parameters. Start out from the 
"large" set, but increase the number of threads (>= # of clients if 
possible, max is 128-n where n~=7).

- Use the right I/O scheduler. Depending on your hardware, either 
"deadline" or "noop" should work best. The default "cfq" probably won't.

- Depending on access patterns, increasing readahead may help as well.
Try values from 1024 to 16384.

The latter two can even be changed on the fly, which makes it really 
simple to find the optimum while your clients are doing real world work.

Notice that 1.4.7 still has a 2 TB size limit for the vice partitions, so 
you want to stay a little bit below unless you go for 1.4.8.

Hope this helps. Let us know what you chose and how well it works and 
performs.

Regards,
 	Stephan

-- 
Stephan Wiesand
   DESY - DV -
   Platanenallee 6
   15738 Zeuthen, Germany