Hi,

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

/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

/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

/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
gmccormack@kronos.com

Hi Gary,

After reading your post I am not quite sure that you have software problem.

<Thorn Puts on his A+ & Network+ hats.>

Your Dell 6650 has 16 GB of Memory, 15 HDs, 2 Pentium Xeon cpus and cooling fans for all of this hardware. Dell says that you have (2) 900watt power supplies.

I would check the following things:

Do you have enough power from the power supply to run your hardware configuration?

Is heat an issue that could be slowing things down?

Is the internal system bus slowing you down? How fast is your raid controller?

Is the fiber channel connection properly configured?

Also I would monitor the traffic on the wire. It is possible the server is fine but that there is excessive traffic on the network causing a slow down in perfomance.

I hope this helps,

Thorn168

Hi Gary,

I forgot to mention one addition thing:

Have you checked the Hard drives for fragmentation?

that could also slow you down.

Thorn168

Hi Thorn,

Thanks for the reply. Power and heat should not be a problem. I just upgraded the Megaraid drivers from Megaraid to Megaraid2 and upgraded to the latest firmware on the LSI card. I also just moved the system to a gigabit subnet and I removed the Broadcomm bcm5700 drivers and teaming and put in TG3 drivers. I have not checked the hard drives for fragmentation but the system has only been in use for less than a year.
I think the CX400 RAID 5 made be configured incorrectly since I have 14 disks in one RAID Group. Thanks again, if you think of anything else please let me know.

Gary

Hi Gary,

Just out of curiosity, Why do you think that OS seems to be slowing you down?

Thorn

Hi Thorn,

Well I am not sure it is the OS but I know the kernel we are using is e34 and the latest from RH is e59. When the system is under a heavy load top shows the system state between 70 to 80% which would indicate that are SCM application is doing something heavy with the kernel. This is all speculation on my part. I am going to move forward with the reconfiguration of our CX400 from a RAID 5 to a RAID 10 and also try loading the latest kernel. Do you know anybody that has done that, I would like to hear how the process went and what the performance results were.

Hi Gary,

I don't know anyone who is using RHEL with a Raid 10 configuration. Although I am curious to see if the Raid 10 setup will improve performance.

Try www.ibm.com/redbooks for Redhat Linux server info. I downloaded 2 redbooks from them on desktop migration. They may have specific redbook on server tuning with redhat linux.

The Kernel may give you the boost that you are looking for since they have improved the code that controls multithreaded processing in Intel processors.

I am still puzzling over the performance problem. Do you have other similar servers or even windows servers that you can compare the performance difference to? If so how well are they performing in comparison?

Are your clients complaining slow access and timeouts?

I want to help you more but I need to know more about the problem first.

Thorn