[SWLUG] Failed Raid 1

[Hugh Saunders]

On 22/01/2008, Justin Mitchell <justin at discordia.org.uk> wrote:
>
> On Tue, 2008-01-22 at 10:48 +0000, Hugh Saunders wrote:
> > My Parents have windows[1] installed on a RAID 1 (mirror)  volume.
> > The raid controller is built into the motherboard and presents the two
> > disks as a single volume to the operating system.
>
> Youll probably find that it isnt hardware raid at all, many motherboards
> have some simplistic raid-assist hardware but that all the real work is
> done in the driver.
>

I think I was fooled into thinking it was hardware raid by their
mention of a BIOS style setup program. I'm not sure which the
motherboard/chipset is but they mentioned "Intel Application
Accelerator" which I think puts it in the ICH5/6 range? And probably
is a software raid. The dmraid readme
(http://people.redhat.com/~heinzm/sw/dmraid/readme)
says "Intel Software RAID" is supported. The knoppix DVD includes
dmraid in it's packages list, so there is a chance of that working.


> i do hope they arent an identical pair.
> you really want to buy each disk from a different manufacturer where
> possible, this reduces the risk of simultaneous failures due to design
> defects.

I had considered this as a possible reason that they both failed
within such a short period of time, I will advise them to buy disks
from different manufacturers.

> > Questions:
> > 1. Is a disk that is half of a Raid 1 volume, the same as a standalone disk?
> >  - Ie does it have the same mbr, partition table, file system etc, or
> > does it have RAID specific markings?
>
> depends on the raid implimentation, it may have added special markers,
> but itll probably just look like a normal disk.

Thanks


> > 2. Should I attempt recovery using individual disks or through the
> > mirrored raid volume?
>
> you didnt say anything about how they had 'failed'
> was it just a couple of read/write errors or have they totally died.

I was vague on that point as I only know what I've been told on the
phone: Pop up systray box saying "RAID in degraded state, one disk
failed" then while backing up, BSOD, then no boot.


Thanks for all the comments :-)

-- 
Hugh Saunders