On Mon, 15 Nov 2010 09:13:26 +1100 Neil Brown <neilb@xxxxxxx> wrote: > Depending on which version of mdadm you are using, the default chunk size > will be 64K or 512K. I would recommend using 512K even if you have an older > mdadm. 64K appears to be too small for modern hardware, particularly if you > are storing large files. According to some benchmarks I found, 64 or 128K still provide the sweet-spot performance on RAID5 and RAID6, especially on writes. http://louwrentius.blogspot.com/2010/05/raid-level-and-chunk-size-benchmarks.html http://blog.jamponi.net/2008/07/raid56-and-10-benchmarks-on-26255_10.html#raid-5-performance http://alephnull.com/benchmarks/sata2009/chunksize.html > I agree with what Mikael and Luca suggested - particularly the suggested for > "--bitmap internal". You really want that. It will also help to increase the --bitmap-chunk value to reduce its performance impact, I suggest using 131072 or more. -- With respect, Roman
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