Question:
All I've seen so far on this topic is hdparm -tT and dd with a bunch of not entirely clear parameters.
What I would like to see: the dependence of read and write speeds on the size of the block and its position. Of course, the program should work from the command line without a graphical environment.
Answer:
iops is exactly what you are asking for. Returns the table BLOCK | SPEED
/dev/md0, 12.00 TB, 32 threads:
512 B blocks: 466.5 IO/s, 233.3 KiB/s ( 1.9 Mbit/s)
1 KiB blocks: 453.2 IO/s, 453.2 KiB/s ( 3.7 Mbit/s)
2 KiB blocks: 445.0 IO/s, 890.1 KiB/s ( 7.3 Mbit/s)
4 KiB blocks: 465.0 IO/s, 1.8 MiB/s ( 15.2 Mbit/s)
8 KiB blocks: 441.4 IO/s, 3.4 MiB/s ( 28.9 Mbit/s)
16 KiB blocks: 444.9 IO/s, 7.0 MiB/s ( 58.3 Mbit/s)
32 KiB blocks: 433.9 IO/s, 13.6 MiB/s (113.7 Mbit/s)
64 KiB blocks: 444.8 IO/s, 27.8 MiB/s (233.2 Mbit/s)
128 KiB blocks: 465.3 IO/s, 58.2 MiB/s (487.9 Mbit/s)
256 KiB blocks: 409.0 IO/s, 102.3 MiB/s (857.8 Mbit/s)
512 KiB blocks: 212.4 IO/s, 106.2 MiB/s (890.8 Mbit/s)
1 MiB blocks: 142.3 IO/s, 142.3 MiB/s ( 1.2 Gbit/s)
2 MiB blocks: 67.1 IO/s, 134.2 MiB/s ( 1.1 Gbit/s)
4 MiB blocks: 40.9 IO/s, 163.7 MiB/s ( 1.4 Gbit/s)
8 MiB blocks: 21.5 IO/s, 171.6 MiB/s ( 1.4 Gbit/s)