diff options
author | NeilBrown <neilb@suse.com> | 2017-04-03 12:11:32 +1000 |
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committer | Shaohua Li <shli@fb.com> | 2017-04-10 10:35:27 -0700 |
commit | 7471fb77ce4dc4cb81291189947fcdf621a97987 (patch) | |
tree | 8b8e0ee2aec838c866e15634c43e3f98215b5b88 /drivers/md/raid10.c | |
parent | 583da48e388f472e8818d9bb60ef6a1d40ee9f9d (diff) |
md/raid6: Fix anomily when recovering a single device in RAID6.
When recoverying a single missing/failed device in a RAID6,
those stripes where the Q block is on the missing device are
handled a bit differently. In these cases it is easy to
check that the P block is correct, so we do. This results
in the P block be destroy. Consequently the P block needs
to be read a second time in order to compute Q. This causes
lots of seeks and hurts performance.
It shouldn't be necessary to re-read P as it can be computed
from the DATA. But we only compute blocks on missing
devices, since c337869d9501 ("md: do not compute parity
unless it is on a failed drive").
So relax the change made in that commit to allow computing
of the P block in a RAID6 which it is the only missing that
block.
This makes RAID6 recovery run much faster as the disk just
"before" the recovering device is no longer seeking
back-and-forth.
Reported-by-tested-by: Brad Campbell <lists2009@fnarfbargle.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid10.c')
0 files changed, 0 insertions, 0 deletions