IBM xSeries 346 Slow Raid Performance

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We recently bought a few used IBM xSeries 346 server each with 2 hard drives. We also bought enough extra hard drives to load all the servers to 6 hard drives. 1 of the servers is having a performance issue in a Raid 5 configuration. Early indications were that the activity lights on the drives would not sync except on identify drive. We noticed that the drives had a vairety of firmware revision on them. We managed to get 6 drives with the same firmware and the server performs great. We change out a drive for a different firmware revision and we have problems. We have run IBM's hard drive firmware updater on all the drives and found a couple that didn't have the latest firmware, so we upgraded them. We still have the same issue of very poor performace if we cross firmware revisions (which IBM has about 30 current versions). We cannot order drives by firmware so we need to get the problem fixed. We did try changing out the raid controller with a second server that does not appear to have any cross firmware issues and the problem remained on the original server. Any clues would help.

 

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Our Raid Controller is k7 with chipset Type 8840.

We have updated all pieces of firmware we have been able to find updates for (Bios, RAID controller, Hard Drive)

We have had great performace if all our drives with firmware C206. We added in a C101 and it worked great after it rebuilt. We put it a JP86 and performance slowed to an absolute crawl after rebuilding. All disk IO processes were slowed down even installing the OS. The activity light on the drives would not sync. The C's would all be in sync and the J would blink about a second later. We have tried multiple drives and keep noticing this effect. We have other servers that are identical that are not having any problems at all.