Re: weird issues with raid1

["NeilBrown" <neilb@suse.de>]

On Tue, December 23, 2008 1:40 am, Jon Nelson wrote:
> More updates:
>
> 1. I upgraded to openSUSE 11.1 over the weekend. The kernel is
> 2.6.27.7-9 as of this writing.
>
> 2. When I fired up the machine which hosts the network block device,
> the machine hosting the raid properly noticed and --re-added /dev/nbd0
> to /dev/md11.
>
> 3. /dev/md11 went into "recover" mode (not resync).
>
> 4. I'm using persistent metadata and a write-intent bitmap.
>

It does seem like you are doing the right thing....

Can you show me the output of both --examine and ----examine-bitmap
on both /dev/sda and /dev/nbd0 just before you --re-add nbd0 to
the array that already contains sda ??
For recovery to use the bitmap, "Events Cleared" on sda must be no
more than "Events" (from --examine) of nbd0.

What you sent doesn't quite have all this information, but it does
show that for nbd0 before it is added to the array:

--examine;
         Events : 7042

--examine-bitmap:
          Events : 5518
  Events Cleared : 5494

This shouldn't happen.  The 'events' from --examine and from
--examine-bitmap should always be the same.  That is how md knows
that the bitmap is still accurate.
This seems to suggest that nbd0 was, for a while, assembled into an
array which did not have an active bitmap.

Thanks,
NeilBrown