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Old 01-25-2005, 02:58 PM   #1
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Question Poor Performance Red Hat AS 2.1, Dell CX400


We are running Red Hat AS 2.1, kernel 2.4.9-e34enterprise on a Dell 6650.
The server has two 2.0 ghz CPUs with a mb of cache and 16 gb (yes 16 gb of RAM). We have a Dell CX400 attached via fiber that has 15 10k 73 gb drives in a RAID 5, 14 disks make up one big LUN and disk 15 is used for hot swap. We have an additional 6650 attached via fiber for failover. We are getting poor performance from the system and I am looking for ways to improve performance. The hdparm number I get from "hdpart -tT /dev/sda" looks like this from the secondary server:

hdparm -tT /dev/sda

Timing buffer-cache reads: 128 MB in 0.32 seconds =400.00 MB/sec
Timing buffered disk reads: 64 MB in 1.29 seconds = 49.61 MB/sec
[root@engaccurev0 shared]# hdparm -tT /dev/sda

Timing buffer-cache reads: 128 MB in 0.32 seconds =400.00 MB/sec
Timing buffered disk reads: 64 MB in 1.85 seconds = 34.59 MB/sec
[root@engaccurev0 shared]# hdparm -tT /dev/sda

Timing buffer-cache reads: 128 MB in 0.32 seconds =400.00 MB/sec
Timing buffered disk reads: 64 MB in 1.06 seconds = 60.38 MB/sec
[root@engaccurev0 shared]#

I am not sure the above means anything. I have talked to Red Hat about going to the latest kernel but I am not sure it will give us the performance increase we are looking for. I am considering changing the CX400 from a RAID 5 to a RAID 1+0. I know my disk space will be cut in half but we need a performance boost. Has any body done this? Can they tell me what they saw for a performanc increase? Any suggestions for increasing performance would be greatly appreciated. Thanks.

Gary McCormack
Old 01-25-2005, 04:44 PM   #2
Registered: Jun 2004
Location: Lawrence, KS
Distribution: Slackware
Posts: 301

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just to compare

Hello gmccormack

hdparm -tT /dev/sdb

Timing buffer-cache reads: 1820 MB in 2.00 seconds = 910.00 MB/sec
Timing buffered disk reads: 188 MB in 3.00 seconds = 62.67 MB/sec

This is with Slackware 10 <2.4.26> on a Seagate ST318453LC (15Krpm) attached to a
Adaptec AIC7899 controler.
Old 01-30-2005, 08:17 AM   #3
Registered: Aug 2004
Distribution: Suse
Posts: 44

Rep: Reputation: 16
FYI Comparison

Here are my stats:

hdparm -tT /dev/hde

Timing buffer-cache reads: 2376 MB in 2.00 seconds = 1186.40 MB/sec
Timing buffered disk reads: 174 MB in 3.03 seconds = 57.38 MB/sec

Athlon64 +3200 with 512MB RAM driving SUSE 9.1 Pro Linux 2.6.5-7.95 on a Maxtor 250GB 7200 RPM drive


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