Re: deadlock with 2.6.9

From: Chuck Ebbert
Date: Fri Nov 12 2004 - 22:50:59 EST

On Sun, 07 Nov 2004 at 09:22:14 +0100 Bernd Eckenfels wrote:

> > Get a real RAID controller (3Ware, not some crappy pseudo-RAID junk.) They are
> > much more reliable than software RAID.
> On what sample do you base this claim?
> Generally hardware raid sooner or later makes problems (especially if you
> run raid5 in degenerate mode or try to rebuild by disk replacing with
> differen/old signature). Also bus hangs are commonly not very well received
> by hw raid firmware or drivers.

I had 28 mirror sets on Compaq SMART2/p controllers in one server (four
controllers, two SCSI channels each, seven disks per channel.) All the disks
on channel A of each controller were mirrored to those on channel B, so even
complete failure of one channel didn't cause a problem.

Once a disk was marked 'failed' in the controller NVRAM there was no way to
convince it that some newly-inserted disk contained valid data.

Booting up with SCSI cables connected wrongly (channels A and B swapped) got you
a nice error message informing you of this fact. Swapping SCSI IDs on different
disks on the same channel was also detected and reported nicely.

And attempting to boot with a bad cable (bent pin) gave a message saying 'either
power down NOW and check cables or I will mark every disk on that channel as

Of course this system was 100% Compaq; even the disks had Compaq firmware
though the labels said IBM. And it was very expensive...

--Chuck Ebbert 12-Nov-04 22:42:32
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