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I have an Dell PowerEdge 830, but after installing a 4:th disk and while copying backup files to this new disk the overall performance of the server just plummet.

The system degrades to a point where it can not be accessed remotely over the network and basically freeze. But as soon as I cancel the copy operation things return to normal.

I can provide more information on the matter, but right now I'm thinking it's related to the bus speed, but why would it be so intense? Is there anything I can do to identify the problem, or has anyone run into a similar problem?

Current disk configuration

  • 3 disks connected to a DELL CERC SATA 1.5/6ch RAID Controller
    • Only two of these disks form a RAID0 array
    • The 3rd disk seems to be unused
  • The RAID array has 3 partitions, something called EISA configuration 31MB (don't know what this is), C: with 132GB and D: with 165GB
  • 4th disk connected to a SATA port on the main board

Copying from the RAID array to the 4th disk kills server performance to a point where it's almost entirely unresponsive.

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If you're running several disks off the same cable, that's probably the issue right there. How is the hardware plugged in? – user3914 Oct 21 '09 at 9:19
3 disks are connected to a RAID controller, (2 of those make out a RAID array, 1 of those disk seem to be unused), the 4:th disk is connected on it's own SATA0 port directly on the main board. – John Leidegren Oct 21 '09 at 9:25
That is peculiar. Perhaps you're saturating the channel, but I've never actually heard of that from SATA drives. I'm giving you +1 for the question. This is interesting. – user3914 Oct 21 '09 at 9:27
thanks, this really puzzles me – John Leidegren Oct 21 '09 at 9:29
More specs please! RAID controller, what types are the other 3 drives (SAS, SATA), and what type of RAID (0,1,5, etc), how are your containers set up, and what OS are you running (yes this might make a difference). – Joseph Kern Oct 21 '09 at 10:44
up vote 2 down vote accepted

Make sure the integrated s-ata isn't running in compatibility mode, and that you have updated drivers for the integrated controller.

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I'm gonna try this out, haven't been able to yet but I'm quite sure I did set the ATA-compatibility mode. It looked like that was the only option that would enable the mainboard SATA ports. I'll have to check back to confirm. Thanks! – John Leidegren Oct 30 '09 at 19:11

CERC == "Cost Effective Raid Controller" which I'm learning means something along the lines of "driver-based software RAID implementation."

Are you sure it's a RAID0? Given the sizes you mention of your partitions, you have 297GB of usable space. Dell didn't ship that with 300GB SATA disks, at least according to this. I'm going to bet that you have 3 160GB SATA disks in a RAID5 with one disk failed. A failed drive in a RAID5 array with a "driver-based software RAID implementation" would peg the CPU on your machine to the point of pain during reads.

I bet if you tried the same file transfer to remote disks you'll have the same performance problems.


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I had this problem as well. In general I noticed that the performance of Dell's SAS controller (i5 or something like that) is very bad. That's why I switched to regular SATA disks which are classes faster than anything attached to Dell's controller...

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Do you have any benchmarks you'd like to share? Just curious. – Joseph Kern Oct 21 '09 at 10:48
In my experience the PERC5i performs quite well. – Roy Oct 25 '09 at 8:14
PERC5i/6i is slower than simple SATA with no RAID? You are terribly wrong here. The only thing they are slow is is during POST/boot, because the controller has to run a sequence which detects the disk WWNs, and checks them for RAID configuration. – dyasny Oct 28 '09 at 15:48

Check to see if the 2 storage controllers are sharing IRQs.

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It's not a requirement, but I would lean towards only using 1 raid controller per disk array. if you want to use another sata stand alone disk, plug it into the mobo, or get another drive controller. I would only have my raid controller control my raid array. I bet your problems would disappear after you moved the stand alone disk off the raid controller.

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