Re: Raid Problem - Unknown File System Type

[Phil Turmel <philip@turmel.org>]

On 11/09/2011 02:57 PM, William Colls wrote:
> On 11/09/2011 01:55 PM, Phil Turmel wrote:
>> Hi William,
>>
>> On 11/09/2011 12:12 PM, William Colls wrote:
>> [...]
>>
>>> I thought, at the time, that I needed to do the create so that the /dev/md0 device would be created properly (new machine had no raid before).
>>
>> That's the "--auto" option, which has sane defaults.
>>
>> [...]
>>
>>> No output from the original setup.
>>
>>> From what you've described so far, a likely possibility is that the original raid 1 was using metadata version 1.1 or 1.2, which put the superblock near the beginning of the disks.  The default "--create" metadata in that old version of mdadm is 0.9, as you can see in your reports.
>>
>> If so, you've likely only lost a tiny bit of data at the end of the volumes where the 0.90 superblock has been written.  (I'm also going to assume that the two disks were in-sync in old box before you moved them, so the re-sync wouldn't do any harm.)
>>
>> A dump of the first 8K of your drives might be helpful here.
>>
>> dd if=/dev/sdb count=16 2>/dev/null |hexdump -C
>>
>> dd if=/dev/sdc count=16 2>/dev/null |hexdump -C
>>
>> Regards,
>>
>> Phil
>>
> 
> Did the dumps to text files. diff shows no difference between the files. Should I be looking for anything particular? There are sections which seem to have data, and several blocks that are all zeros, but I don't see any particular patterns, and only a very few obvious text strings.
> 
> Thanks for your interest and help.

I was expecting them to be nearly identical, unless they're corrupted.  I was particularly interested to see if an MD signature shows up at offsets 0 or 1000H, with device names at 20H or 1020H.

Or there might have been a partition table or boot loader showing, or fragments thereof.

I can't see them, of course.  (Hint.)

Phil