Re: 3Ware SATA Raid 9550SX Performance - different blocksizes
by Simon at 12:52 10/09/07 (Forum::Technical Advice::General)
Results of some vmstat tests using different blocksizes in the read/write of 3GB of data.


dd if=/dev/sda of=/dev/null bs=X count=y followed by dd if=/dev/zero of=/3GBfile bs=X count=Y

... foreach each of X = 512B, 1K, 2K, 4K, 8K, 16K, 32K, 64K, 128K, 256K and 512K and Y is the appropriate multiplier to get to 3GB.

In answer to the question "does changing the blocksize make any difference?" the answer is "No".

Attached PDF graphs the results of a whole run - again we've got fairly solid 80000 blocks/s on reads and very bursty block/s on writes, with lots of processes being blocked when writing.

PDF file (111 K) 3GB read/write with various block sizes from 512B to 512K
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