Hi Neil,
testing the following scenario:
1) create a raid1 with drives A and B, wait for resync to complete
(verify mismatch_cnt is 0)
2) drive B fails, array continues to operate as degraded, new data is
written to array
3) add a fresh drive C to array (after zeroing any possible superblock on C)
4) wait for C recovery to complete
At this point, for some reason "bitmap->events_cleared" is not
updated, it remains 0, although the bitmap is clear.
5) grow the array by one slot:
mdadm --grow /dev/md1 --raid-devices=3 --forc
6) re-add drive B back
mdadm --manage /dev/md1 --re-add /dev/sdb
MD accepts this drive, because in super_1_validate:
/* If adding to array with a bitmap, then we can accept an
* older device, but not too old.
*/
if (ev1 < mddev->bitmap->events_cleared)
return 0;
Since events_cleared==0, this condition DOES NOT hold, and drive B is accepted
7) recovery begins and completes immediately as the bitmap is clear
8) issuing "echo check > ..." yields in a lot of mismatched
(naturally, as B's data was not synced)
Is this a valid scenario? Any idea why events_cleared is not updated?
Kernel is 3.8.13
Thanks,
Alex.
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