Messages in this thread | | | Date | Sat, 01 Mar 2008 15:04:29 -0500 | From | Bill Davidsen <> | Subject | Re: very poor ext3 write performance on big filesystems? |
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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@tmr.com> "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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