Redundant NFS storage setup (part 3) : The disappointingPERC5/E (solved?)

[Landreth, Kevin]

Using setra won't help with writes IIRC.  Has write performance seen any
difference?  In the applications where I use a Perc5 card, writes are my
biggest performance problem and I'd like to see if you write performance
is still suffering.  Using setra will help with software raid just the
same too I believe so I wouldn't write your problem off as "solved" just
yet.

Also, could you try ext3 with -E stride=32 (for 128K) and stride=16 (for
64K) and see if you still have the performance issues you had before.  I
know this may not be ideal for your application but testing with two
file systems provides better conclusive answers for everyone beyond a
reasonable doubt.

Thanks for all the testing, this is really useful data you are providing
everyone.

--
Thanks,
Kevin Landreth, RHCE
Technology Architect 


-----Original Message-----
From: linux-poweredge-bounces at dell.com
[mailto:linux-poweredge-bounces at dell.com] On Behalf Of Matthias Saou
Sent: Thursday, January 03, 2008 9:46 AM
To: linux-poweredge at dell.com
Subject: Re: Redundant NFS storage setup (part 3) : The
disappointingPERC5/E (solved?)

Hi all,

Looking for information on XFS filesystem options, I found this very
instructive thread :

http://oss.sgi.com/archives/xfs/2007-09/msg00322.html

I read about this simple change in one of the posts, which improved
performance a lot for the person making the benchmark, so I ran it :
# blockdev --setra 16384 /dev/sdb

I now get 500-520MB/s read speed with hardware RAID5 where I used to
get 30-35MB/s... pretty amazing, I must admit.

Looking at the man page, this just sets a read-ahead value... I'm
puzzled yet very happy!

Would any of the others who reported slow read speeds with their PERC5s
and MD1000s care to also try it and report back to the list?

I'll continue digging, but in the meantime, it seems like my "problem"
might be solved.

Matthias

-- 
Clean custom Red Hat Linux rpm packages : http://freshrpms.net/
Fedora release 8 (Werewolf) - Linux kernel 2.6.23.9-85.fc8
Load : 0.50 0.65 1.03

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