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I recently acquired 2 PE 2950s. They are identically configured, matching cards and firmware. The drive are also configured the same, seagate 15k 300gig in raid 10. writeback and adaptive readahead, cached IO. dual quad core x5355 procs, 32 gig ram. BIOS settings are also identical. perc 5i.

one performs flawlessly. unixbench give it a score of 3000+

the other is a dog, can't even make 1000 on unixbench, very poor IO speed and bad throughput scores.

to test I put a new perc and battery/cables in the bad server, and swapped the raid disk sets between them. After letting the battery charge and waiting for init to finish, still no difference at all in the scores. Running online diags finds no hardware faults, except the broadcom nic test doesn't seem to run (eth0 certainly works). No warnings in openmanage either, or anything of note in the logs.

Can anyone suggest what the fault might be in this case?

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I think you'll need to engage Dell's support channels to get this resolved. –  Chris Thorpe Oct 5 '11 at 0:49
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up vote 1 down vote accepted

well, mystery solved and we're all kicking ourselves.

One of the 8x 4 gig ram sticks was bad, even though it came up OK in tests many tests.

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Please mark this as your accepted answer :) –  pauska Oct 7 '11 at 12:33
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If it's strictly a disk I/O problem and you've swapped both the PERC and the drives for known good units, then it sounds like there might be a problem with the backplane (and/or the backplane SAS cable). If necessary, you could replace these with used parts for about $70 (backplane) and/or $20 (cable).

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well, ruled out the cable too. As the only stuff in there we really want is the disks and the cpus will swap those into another, simpler than changing all the other remaining cards out. –  Ursula Oct 6 '11 at 3:52
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