Re: mdadm -E won't examine loop back device, works ok on source disk

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Thanks for your reply but setting IMSM_NO_PLATFORM seems to have no effect...

% export IMSM_NO_PLATFORM=1
% echo $IMSM_NO_PLATFORM
1

% mdadm -V
mdadm - v3.2.3 - 23rd December 2011

% mdadm -E -v /dev/loop2
mdadm: No md superblock detected on /dev/loop2.

% export IMSM_NO_PLATFORM=""
% echo $IMSM_NO_PLATFORM

% mdadm -E -v /dev/loop2
mdadm: No md superblock detected on /dev/loop2.

And trying to assemble fails...
export IMSM_NO_PLATFORM=1
% mdadm --assemble /dev/md0 /dev/loop1 /dev/loop2
mdadm: Cannot assemble mbr metadata on /dev/loop1
mdadm: /dev/loop1 has no superblock - assembly aborted

Regards,
V

On Sun, Apr 22, 2012 at 5:58 PM, NeilBrown <neilb@xxxxxxx> wrote:
> On Sun, 22 Apr 2012 17:00:04 -0400 Veedar Hokstadt <veedar@xxxxxxxxx> wrote:
>
>> Consider a SATA drive /dev/sdb which is a member of an imsm RAID0 array...
>>
>> % sum /dev/sdb
>> 25645 156290904
>>
>> The drive was imaged to a file without error and mounted as a loopback device...
>>
>> % sum /dev/loop2
>> 25645 156290904
>>
>> The checksums match as expected. But I can not examine the loopback I get....
>>
>> % mdadm  -E -v /dev/loop2
>> mdadm: No md superblock detected on /dev/loop2.
>>
>> But I can examine the physical source drive /dev/sdb...
>>
>> % mdadm  -E -v /dev/sdb
>> /dev/sdb:
>>           Magic : Intel Raid ISM Cfg Sig.
>>         Version : 1.0.00
>>     Orig Family : e92a11d9
>>          Family : e92a11d9
>>      Generation : 00001608
>>            UUID : 25137636:2ff64e75:10ae5444:4e8f609b
>>        Checksum : e1237b20 correct
>>     MPB Sectors : 1
>>           Disks : 2
>>    RAID Devices : 1
>>
>>   Disk01 Serial : 8068C3QVT
>>           State : active
>>              Id : 00010000
>>     Usable Size : 312577294 (149.05 GiB 160.04 GB)
>>
>> [Volume0]:
>>            UUID : 72acd5fa:35c5a901:995af79b:83a29de1
>>      RAID Level : 0
>>         Members : 2
>>       This Slot : 1
>>      Array Size : 625154048 (298.10 GiB 320.08 GB)
>>    Per Dev Size : 312577283 (149.05 GiB 160.04 GB)
>>   Sector Offset : 0
>>     Num Stripes : 1221004
>>      Chunk Size : 128 KiB
>>        Reserved : 0
>>   Migrate State : idle
>>       Map State : normal
>>     Dirty State : clean
>>
>>   Disk00 Serial : 809BC541T
>>           State : active failed
>>              Id : 00000000
>>     Usable Size : 312577294 (149.05 GiB 160.04 GB)
>>
>> I'm trying to recover data from a failed RAID0.
>> I can successfully reassemble the RAID0 from the image files using
>> other proprietary recovery software.
>> But I would like to get it working with mdadm if at all possible.
>> Any ideas?
>>
>
> Try setting  IMSM_NO_PLATFORM in the environment:
>
>  IMSM_NO_PLATFORM=1 mdadm -E -v /dev/loop2
>
> or
>
>  export IMSM_NO_PLATFORM=1
>  mdadm -E -v /dev/loop2
>
> I think this is fixed in more recent mdadm.  You still need IMSM_NO_PLATFORM
> to create or assemble an array, but not just to look at it.
>
> NeilBrown
>
>
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