Dell PE4600 RAID5 server failing

Derek Ragona derek at
Wed Nov 14 07:52:08 PST 2007

At 09:00 AM 11/14/2007, Barnaby Scott wrote:
>I suspect I already know the answer to this, which is that the trouble I 
>am having is nothing to do with the OS at all, but I have to ask, because 
>I am otherwise up against a total brick wall!
>I bought a second-hand Dell Poweredge 4600 and installed FreeBSD 6.2 
>earlier this year. I had it set up with RAID5 using its PERC3/DC 
>controller, with 7 x 73GB disks (+ 1 hot spare). So far so good, and it 
>worked faultlessly as a Samba server for several months.
>At the beginning of October, it went down, reporting a mismatch between 
>the configuration on the NVRAM and the disks. With help from Dell support, 
>I managed to recreate the RAID array and it worked again for a month.
>In early November it happened again, and has kept happening since. At one 
>point it appeared that the backplane was faulty, so I replaced that, but I 
>cannot keep the server up for more than a day or so without this 
>'mismatch' poblem.
>What about diagnostics on the hardware you may ask? I have run all the 
>diagnostic tools that Dell can supply - several times - and the server 
>declares itself to be totally fault-free.
>My specific questions therefore:
>Is there any way at all that FreeBSD could be invloved with this problem? 
>(I did notice for example that the Dell PERC3/DC controller was not in the 
>list of supported hardware - but then again, why did it work for several 
>Can I use FreeBSD to tell me anything about the fault that Dell's 
>diagnostic tools haven't found?
>(I do hope someone might be able to help - Dell are trying to get me to 
>switch to a 'supported' OS!)
>Barnaby Scott

It doesn't sound like any OS issue as you set up the RAID outside the 
OS.  It may be a bad drive or drive(s).  Most RAID drives have RAID 
information written to the drives, and if this becomes unreadable you will 
have RAID faults.

Another likely culprit is heat.  Overheating drives often fail.  Are you 
sure the temperatures in the drive enclosure is OK?

If you can, run diagnostics on the drives, this usually requires running 
these with the drives taken out of the RAID array though.


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