Also, Brian, how much RAM does your box have?
To expound on Rob's first point, the spindle count of a RAIDZ (or Z2)
set is important. It's generally urged to keep the disks that
comprise a raidz(2) set in the single digits and no more than 10 or
so (note this is not per pool, but per set. You can of course have
multiple sets in a pool, and that would also be better in terms of
fault tolerance)
/dale
On Jul 11, 2007, at 8:11 PM, Robert Banz wrote:
A couple things to check, Brian...
1) How large is your RAID-Z2 pool (# of spindles)? If it's rather
large (say, above 8), you might be running into problems from that.
2) Check to see if your fileserver process is fully resident in
memory (not swapped out.) ZFS's ARC can get VERY greedy and end up
pushing out real stuff to swap. If you've got a callback table
size on your fileserver, there will be quite a few chunks of memory
that it uses which may look like good candidates for swapping-out
because they don't get accessed much -- but when they do, it'll
drag your fileserver to a crawl for the time when its got to swap
them in. If this is the case, figure out how much ram you can
dedicate to the ARC, and pin its maximum size. (see: http://
www.solarisinternals.com/wiki/index.php/
ZFS_Best_Practices_Guide#Memory_and_Dynamic_Reconfiguration_Recommenda
tions )
-rob
On Jul 11, 2007, at 16:49, Brian Sebby wrote:
Hello,
I've been getting intermittant reports of slow read performance on
a new
AFS file server that I recently set up based on ZFS. It is using
locally
attached disks in a RAID-Z2 (double parity) configuration. I was
wondering
if anyone might be able to provide any ideas for tuning /
investigating
the problem. The slow performance that's been reported seems to
be against
a RW volume with no replicas.
Right now, I am using OpenAFS 1.4.4 with the "no fsync" patch. The
options I'm using for the fileserver are "-nojumbo" and "-nofsync".
I've also set the ZFS parameters "atime" to "off" and "recordsize"
to "64K" as recommended in Dale Ghent's presentation at the OpenAFS
workshop.
There are a bunch of file server options that I'm not sure if they
would
help or not. Any advice would be appreciated as I'm looking at
ZFS-based
file servers for some new file servers I'm setting up, but my
experience
so far has been mostly with the OpenAFS 1.2 inode-based file server.
Brian
--
Brian Sebby ([EMAIL PROTECTED]) | Unix and Operation Services
Phone: +1 630.252.9935 | Computing and Information Systems
Fax: +1 630.252.4601 | Argonne National Laboratory
_______________________________________________
OpenAFS-info mailing list
[email protected]
https://lists.openafs.org/mailman/listinfo/openafs-info
_______________________________________________
OpenAFS-info mailing list
[email protected]
https://lists.openafs.org/mailman/listinfo/openafs-info
--
Dale Ghent
Specialist, Storage and UNIX Systems
UMBC - Office of Information Technology
ECS 201 - x51705
_______________________________________________
OpenAFS-info mailing list
[email protected]
https://lists.openafs.org/mailman/listinfo/openafs-info
