On Friday 2013-09-06 10:05, Andrey Borzenkov wrote:
So a RAID with 64k stripes & 12 data disks would have a stripe size of 768k. That stripsize is the optimal I/O size (and it isn't divisible by 2).
I cannot reproduce this with at least MD RAIDs in modes 0 5 and 6 using 64k×12 devices. The filesystem created on it reports 4096 for st_blksize, as does fstat on a block device fd when directly opened. So if you can describe your RAID more thoroughly..
Out of interest - what /sys/block/mdX/queue/optimal_io_size says?
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