HDD performance notes

The real transfer rate is about 13-14 Mb/sec. My usual test is:

# time dd if=/dev/zero of=disk_file_1 count=2000000
2.850u 11.490s 1:11.65 20.0%    0+0k 0+0io 105pf+0w
# time dd if=/dev/zero of=disk_file_2 count=2000000
2.600u 11.470s 1:16.66 18.3%    0+0k 0+0io 128pf+0w
# time dd if=disk_file_1 of=/dev/null
2.610u 7.790s 1:11.04 14.6%     0+0k 0+0io 250105pf+0w
# time dd if=disk_file_2 of=/dev/null
2.440u 7.900s 1:14.97 13.7%     0+0k 0+0io 250128pf+0w
i.e. about 70 seconds for 1Gb. The idea to write 2 huge files is to compensate an influence of in-memory system buffers.

hdparm reports a bit more:

# hdparm -t /dev/hda
 Timing buffered disk reads:  64 MB in  4.00 seconds = 16.00 MB/sec
A few experiments with hdparm resulted slower transfer rate, so the default settings seems reasonable.


Comments and questions to Evgeny Rodichev, er@sai.msu.su
Last updated 31.05.2001.