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schweik
Asked: 2021-07-14 12:14:27 +0800 CST

How to use mdadm to assemble arrays from crashed windows server

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I got 12 hard disks from completely crashed server, some of them are failing, too. I successfully saved bit copy of all of them, even not always error free. I found 512MB superblock on each end of disk starting with a word DSREGION. The 512MB of space is not heavily used and from some text fragments one can judge, that the built-in RAID controller was some LSI model. The question remains: how can I assemble the RAID arrays using mdadm. How can I tell the mdadm where it can read the superblock while the command:

# mdadm -E /dev/loopX

does not detect superblock, even if DDF is set explicitly:

# mdadm -E -e DDF /dev/loopX

If there is a hint how to parse the 512MB superblock I can do the parsing manualy and then I can assemble the RAID arrays explicitly using mdadm -A.

Or if there is a possibility to tell mdadm where it has to look for the superblock metadata.

J.

P.S. I hoped I can find something useful at www.snia.org but did not find any detail.

raid mdadm metadata

1 Answers

  1. You don't use mdadm because it cannot handle this job. It has only very limited support for disks that were in hardware RAID arrays, to wit: DDF, and not everyone used that format.

    Instead you should be using dmraid to attempt to explore and recover this array. It supports a variety of software, hardware and fake RAID formats. On a recent Linux system it will support:

    $ 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

    Connect the copies of all the disks you made to a system, turn the computer on, and use dmraid -r to see if a set of RAID devices was detected, dmraid -s <set name> to get properties of the set, dmraid -b to see the status of all block devices that may be part of a set, and if everything looks ok, dmraid -ay <set name> will activate the RAID array.

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