[RndTbl] Big-endian RAID5 recovery problem

Adam Thompson athompso at athompso.net
Mon May 1 17:33:11 CDT 2017

On 2017-05-01 16:59, Anthony Youngman wrote:
> Get hold of lsdrv, and see what that tells you. (Look at the raid wiki
> for details.) I don't know if it will have endian issues, but if it
> doesn't an expert will probably be able to chime straight in and tell
> you the create command.

Ah!  And that took me straight to the "asking for help" page.

The raw data is here: 

To summarize:
* smartctl either fails to run or shows nothing wrong (depending on the 
vintage of drive, maybe?);
* mdadm --examine fails to read the superblock because of the endianness 
issue (see 
* lsdrv fails to report any useful MD topology information I could see 
(other than confirming that each md device had four members, one 
partition on each drive)

I also see 3 "FD" type partitions on each disk, but lsdrv only 
identifies *2* of them as belonging to an MD array.  Not sure what's up 
with that.

> The other thing is, read up on overlays because, if you overlay those
> disks, you will be able to "create" without actually writing to the
> disks. That way you can test - and even do a complete backup and
> recovery - without ever actually writing to, and altering, the
> original disks.

Currently reading, thanks.  Didn't know overlays could be used for block 

Spinning up a QEMU instance of Linux-PPC or Linux-MIPS with the disks in 
pass-through mode has also been mentioned, but... ugh.  Anecdotal 
reports from the web suggest that doing so would just be opening up a 
second rabbit hole in addition to the one I'm already headed down.


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