Re: nfs performance problem

["Matt Heaton" <admin@0catch.com>]

I didn't understand?  What is a good indication of poor seek time?  The high
number for TPS?  I thought a high number meant the drive was handling a huge
amount of transactions per second, and not necessarily slow.  I would LOVE
to
have my NFS servers push out 500 TPS on iostat.  I have 10 webservers that
each ask for between 10-25 files per second from our 3ware 7850 controllers.
We get about 200 TPS on the NFS server.  Much more and the clients become
VERY SLUGGISH, and I get blocked R processes in vmstat on the client.
Sometimes
20-40 blocked R processes in vmstat.  As soon as I offload some of files
from a busy
NFS server to another NFS server then the clients settle down and everything
works
great again, but I only get 1-1.5MB out of each NFS server before this
happens!
I can get really high TPS out of the server LOCALLY when I do copies etc,
its just
over NFS with a huge amount of really small files that everything stinks.

L8r...
Matt



> We have a couple of NFS servers with 3ware cards.  One is a 3ware 7850 (8
> Maxtor 160GB - 5400RPM) and one is a 3ware 7500-12, both configured with
> RAID 5 + Hot Spare.  I have all the latest NFS patches applied.  If I
access
> an NFS mounted directory on one of these systems and copy a bunch of
little
> files (1-2KB), I get 150-250 tps.  If I access larger files (90% > 1MB
each)
> I will normally see 25-60MB/s transfer with 500-700 tps, with peaks of
over
> 1000 tps - A good indication that disk seek is to blame for the problem
with
> the small files.
>
> Thanks,
> -Byran
>
> From: "Matt Heaton" <admin@0catch.com>
> To: "poczta.dotcom.pl" <myciel@dotcom.pl>,
> <nfs@lists.sourceforge.net>
> Subject: Re: [NFS] nfs performance problem
> Date: Tue, 5 Nov 2002 13:22:25 -0700
>
> I have 3ware cards as well (2 7500 Series 8 drive), just like yours.  ALso
> with 120 GIG drives (7200)
> RPM.  Whever I get 150-200 tps in iostat then my NFS runs SO SLOW.  I also
> only get 1 MB, to 1.5 MB
> over NFS.  The local speed seems to be ok, not great though.   MY OPINION
is
> that this is because of seek time on the raid
> array.   I am serving very small files, just like you are.  I am
requesting
> about 200-300 files per second from
> each NFS server.  So even though our throughput of only 1.5 MB isn't high.
> The number of files per second is
> actually quite high, and causes things to slow down because of seek time
> issues.  PLEASE GIVE US CACHEFS SOMEONE??
>
> Does anyone have experience with IDE Raid arrays that get over 250 tps in
> iostat that work fine?  I would
> be VERY VERY VERY interested to find out.
>
> L8r...
>
> Matt
>
>
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