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author | Jonathan Brassow <jbrassow@redhat.com> | 2013-02-21 13:28:10 +1100 |
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committer | NeilBrown <neilb@suse.de> | 2013-02-26 11:55:33 +1100 |
commit | 9a3152ab024867100f2f50d124b998d05fb1c3f6 (patch) | |
tree | 15b97c56d117340fa5db609ced6e0d51a91f2f37 /Documentation | |
parent | 475901aff15841fb0a81e7546517407779a9b061 (diff) | |
download | op-kernel-dev-9a3152ab024867100f2f50d124b998d05fb1c3f6.zip op-kernel-dev-9a3152ab024867100f2f50d124b998d05fb1c3f6.tar.gz |
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
This patch addresses raid arrays that have a number of devices that cannot
be evenly divided by 'far_copies'. (E.g. 5 devices, far_copies = 2) This
case must be handled differently because it causes that last set to be of
a different size than the rest of the sets. We must compute a new modulo
for this last set so that copied chunks are properly wrapped around.
Example use_far_sets=1, far_copies=2, near_copies=1, devices=5:
"far" algorithm
dev1 dev2 dev3 dev4 dev5
==== ==== ==== ==== ====
[ A B ] [ C D E ]
[ G H ] [ I J K ]
...
[ B A ] [ E C D ] --> nominal set of 2 and last set of 3
[ H G ] [ K I J ] []'s show far/offset sets
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'Documentation')
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