Re: Software VS Hardware Raid
On Mon, 28 Jan 2002 13:01, Jason Lim wrote:
> Case 1)
> I replaced one of the disks with an old disk with bad blocks and strange
[...]
> My question: if this was hardware RAID 1... would this have happened?
> Would the hardware RAID controller recognise the problem, and only stop
> briefly, then try the second disk automatically and transparently?
Yes! That is the big advantage of hardware RAID over software RAID!
> Case 2)
> I simulated errors by connecting a flaky IDE cable to one of the drives. I
> was hoping the software RAID would either compensate by doing most of it's
> reading from the good drive (with a good cable) or labelling the flaky
> cable/drive as bad, but instead it started slowing down, and writing to
> the array was taking much longer and strange errors starting occurring
> during writing.
>
> My question: would hardware raid have handled this situation any better?
If (as I guess) the drive never returned a fatal error then maybe not.
However hardware RAID may be smarter about such things and may just mark a
drive as bad because it has to re-try some reads.
I suggest talking to Neil Brown about this, what you describe sounds like a
deficiency in software RAID to me.
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