SC1345 / Perc5 - woeful disk performance

Chris_Purcell at Chris_Purcell at
Fri Apr 27 03:57:38 CDT 2007


By default, on newly created arrays on the Perc5 controllers, the cache
memory is disabled.
Check that the array settings show that write back caching is enabled. 

Chris T. Purcell
Dell Services
EEC Gold Server Analyst
Phone: 1-800-945-3355 ext 7286090
Dell Services Website

How am I doing? Email my manager John Bailey at: John_S_Bailey at
with any feedback.

-----Original Message-----
From: linux-poweredge-bounces at
[mailto:linux-poweredge-bounces at] On Behalf Of Matthew Geier
Sent: Friday, April 27, 2007 2:10 AM
To: linux-poweredge-Lists
Subject: SC1345 / Perc5 - woeful disk performance

 I've just set-up a 1435 with RHEL5 and have found that an otherwise
fine system has absolutely woeful disk performance. (RAID 1 mirroring, 2
x 500 GB ATA)  If a large copy is going on (like some one scping in a
few gig of data files), the system becomes very sluggish and
unresponsive - but anything only consuming CPU continues to fly along

 I've seen a number of complaints about the poor performance of the
Perc5s but little on how to tune them up a bit. Can they be tuned to
reasonably performance or is the perc5 simply a bad design ?

 I also downloaded the LSI tools as pointed to by the site,
hoping to find some tuning parameters to play with, only the 'Mega' tool
set doesn't believe I have a LSI controller fitted. (Although lcpci says
I do :-)

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