Getting started the hard way with RAID

Kevin O'Gorman kogorman at
Fri Dec 2 17:44:28 UTC 2011

On Fri, Dec 2, 2011 at 1:30 AM, Marius Gedminas <marius at> wrote:
> On Thu, Dec 01, 2011 at 06:56:30PM -0800, Kevin O'Gorman wrote:
>> I'm in the late stages of recovering a broken system.  The original
>> had a hardware raid controller managing a mirror set that contained
>> some stuff that was not backed up. Fortunately, one reason it wasn't
>> backed up is that it wasn't really vital.  Nevertheless, I'd like to
>> get at that stuff.
>> The hard part is that I no longer have that RAID controller, just the
>> two drives.  The controller was a 64-bit PCI card, and the new mobo
>> cannot handle it.
> Have you googled for the model and manufacturer of that RAID controller?

Not yet, but I will.  It was a 3ware 9550SX controller.

> AFAIU most hw RAID solutions have their own custom data/metadata formats.
> Chances are you can't access the data easily without a working hardware
> RAID controller of the same manufacturer, but perhaps you're in luck,
> and your particular metadata format is supported by dmraid.
> I'm not familiar with dmraid, unfortunately, but I've glanced at the
> manual page online, and it seems to support some kind of autodiscovery.
> Have you tried it?

I have not really tried much of anything, but I will.  Up to now I've
been too busy getting the urgent stuff back online.  Well, urgent as
hobbies go anyway.

Plus I've been reluctant to fool with things that might harm the data.

The controller was my first experiment with RAID, and I've decided it
was a bad fit to my situation.  As a hobbyist, I don't have spare
drives to drop in when one goes down, I don't have a spare motherboard
to support the controller, or a spare controller, when things go
south.  Not having used this stuff before, it hadn't occurred to me to
worry if the on-disk format was proprietary, but now I see the

I'm probably not going to implement software RAID either, except to
the extent it might make it easier to get at the old RAID stuff.  I've
worked out a nice set of scripts to do backups to "external" drives in
external drive docks, and I have six 2TB sata drives dedicated to
archival storage.  This even supports off-site storage.

> Marius Gedminas

Kevin O'Gorman, PhD

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