Raw disk I/O

[Craig Leres]

(Sorry to jump into this so late but it seems like I never have time to
read news.)

Folks interested in raw disk I/O will also be interested in the little
disk bench mark package we've thrown together. Eventually, I'd like to
it to include a complete tutorial on How To Tune Your Filesystem; for
now the (limited) documentation really only deals with how to measure
raw disk speeds.

The package is easy to use; the primary part is the "disktest" script
which does raw reads at block sizes ranging from 4k to 128k. There's a
simple line fitting program that allows you to munch "disktest" runs
down to the throughput (in KB/sec) and fixed overhead (in ms) numbers.
For example, I've measured 2094.07 KB/sec, 1.49 ms on my Sun 3/180
which runs SunOS 3.5 and has Fujitsu M2344's on an Interphase 4400
controller. There are also some scripts for use with xgraph.

The disktest package is available via anonymous ftp from the host
ftp.ee.lbl.gov (128.3.254.68) in the file disktest.shar.Z. As usual,
use binary mode for best results.

		Craig