My main interest is to understand why 'check' does not actually check.
I already know how to fix the problem, by writing to the location I
can force the pending reallocation to happen, but then I will not have
the test case anymore.
The OP asks for a specific solution, but I think that the 'check' action
should already correctly rewrite failed (i/o error) sectors. It does not
always know which sector to rewrite when it finds a raid6 mismatch
without an i/o error (with raid5 it never knows).
Eyal
On 02/25/14 01:14, Wilson Jonathan wrote:
# echo 3 >'/proc/sys/vm/drop_caches'
# dd if=/dev/md127 of=/dev/null count=$((20*1024*1024))
20971520+0 records in
20971520+0 records out
10737418240 bytes (11 GB) copied, 13.5717 s, 791 MB/s
Note that I do not expect to get an error because reading the array will not read the P/Q checksums
(it assumes good data and avoids the calculations overhead of verifying P/Q).
BTW, due to the use of a buffer layer I could have done the whole test using 4k blocks rather than
sectors, but it makes no difference in this case.
Eyal
I wonder, could you not use dd to perform a "refresh"?
dd if=/dev/md127 of=/dev/md127 count=... bs=....
As that would force a re-calc and write of P & Q and data.
That said, its just a "could you/would it" suggestion not a "do it" due
to the inherent dangers of dd.
--
Eyal Lebedinsky (eyal@xxxxxxxxxxxxxx)
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