Andreas Dilger wrote:
I'm CCing the linux-raid mailing list, since I suspect they will be
interested in this result.
I would suspect that the "journal guided RAID recovery" mechanism
developed by U.Wisconsin may significantly benefit this workload
because the filesystem journal is already recording all of these
block numbers and the MD bitmap mechanism is pure overhead.
Thanks for sharing these numbers. I think use of a bitmap is one of
those things which people have to configure to match their use,
certainly using a larger bitmap seems to reduce the delays, using an
external bitmap certainly help, especially on an SSD. But on a large
array, without a bitmap, performance can be compromised for hours during
recovery, so the administrator must decide if normal case performance is
more important than worst case performance.
--
Bill Davidsen <davidsen@xxxxxxx>
"Woe unto the statesman who makes war without a reason that will still
be valid when the war is over..." Otto von Bismark
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