Thanks for continuing to mull this one :-)

On 04/11/17 13:46, Wols Lists wrote:

quoted

I am pretty sure that is trashed, but I like to try and understand these
things !

More for Neil, this, but I've had a nasty thought. Did you reboot at all
(as in clean shutdown, not crash and restart) at any point during this?
I get the impression you might not have.

That I cannot remember to be honest. As I previously mentioned I *think*
it may have fallen over or crashed during the first rebuild but my
memory of exact events back then is hazy. I can try and fire it up and
check the logs - maybe they will have some history.

Because that *could* explain the missing superblocks! I think raid
updates the superblock every time it moves the rebuild window, so it
should get rewritten to disk regularly. BUT. Is it possible that it was
sitting in the disk cache when the system crashed?

I find it hard to believe that's the case, but it could explain at least
some of it (doesn't explain why those drives had mbr's, though).

I'm pretty sure the cards in use are that old they have precious little
cache in them. However that might not be the case.

I'll go check if I can see anything in any of the logs.

B. Rgds
John

--

PS - I seem to remember I should do reply to all on this list but can't
see where I might have read that ! Please let me know if that is wrong