Getting started the hard way with RAID

Kevin O'Gorman kogorman at gmail.com
Sat Dec 3 17:46:35 UTC 2011


On Sat, Dec 3, 2011 at 7:16 AM, Marius Gedminas <marius at pov.lt> wrote:
> On Fri, Dec 02, 2011 at 09:44:28AM -0800, Kevin O'Gorman wrote:
>> On Fri, Dec 2, 2011 at 1:30 AM, Marius Gedminas <marius at pov.lt> 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.
>
> $ dmraid -l
> asr     : Adaptec HostRAID ASR (0,1,10)
> ddf1    : SNIA DDF1 (0,1,4,5,linear)
> hpt37x  : Highpoint HPT37X (S,0,1,10,01)
> hpt45x  : Highpoint HPT45X (S,0,1,10)
> isw     : Intel Software RAID (0,1,5,01)
> jmicron : JMicron ATARAID (S,0,1)
> lsi     : LSI Logic MegaRAID (0,1,10)
> nvidia  : NVidia RAID (S,0,1,10,5)
> pdc     : Promise FastTrack (S,0,1,10)
> sil     : Silicon Image(tm) Medley(tm) (0,1,10)
> via     : VIA Software RAID (S,0,1,10)
> dos     : DOS partitions on SW RAIDs
>
> No 3ware here.  A quick Google seems to confirm that dmraid is mostly
> for fakeraid devices, while 3ware is a real hardware RAID controller.
>
> (I'm not sure what the difference is -- so the RAID logic runs on an
> embedded CPU on the daughter card instead of your main CPU, which makes
> performance better, but why would that have any impact on on-disk
> metadata formats?)
>
> Looks like you may need to buy a 3ware RAID card if you want to recover
> your data.

Maybe not.  I just worked up the courage to try dmraid.  So far, I've
only tried discovery, but it's promising:
root at treat:~# dmraid -r
/dev/sdd: ddf1, ".ddf1_disks", GROUP, ok, 976494592 sectors, data@ 0
/dev/sdb: ddf1, ".ddf1_disks", GROUP, ok, 976494592 sectors, data@ 0
root at treat:~#

That's exactly the two disks that had the mirror halves, and the size
is convincing.  I don't understand everything it's showing, and I
haven't had the courage to actually turn it on yet....


> Marius Gedminas
> --
> #define QUESTION ((bb) || !(bb)) /* Shakespeare */

Damn, that's funny!



-- 
Kevin O'Gorman, PhD




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