On 11/09/2011 02:57 PM, William Colls wrote:

On 11/09/2011 01:55 PM, Phil Turmel wrote:

quoted

Hi William,

On 11/09/2011 12:12 PM, William Colls wrote:
[...]

quoted

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.

[...]

quoted

No output from the original setup.

quoted

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