Re: Software VS Hardware Raid
Sincerely,
----- Original Message -----
From: "Russell Coker" <russell@coker.com.au>
To: "Jason Lim" <maillist@jasonlim.com>; <debian-isp@lists.debian.org>
Sent: Monday, January 28, 2002 2:26 PM
Subject: 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!
Its sounding more and more like software RAID, while cheaper, isn't as
reliable (although it may have more flexibility) as hardware 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.
Will do, as soon as I've found out the right IDE Hardware RAID card.
Deadline getting uncomfortably close to implementing this.
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