iostat

[beginner]

here comes a stupid question.

i read lots of book saying that i can use iostat to see if
system is i/o bound, but when use iostat, it only tells
you how many kr/s, or kw/s , it didin't tell you if the system
is i/o bound, how can i know if kw/s if more than what number means system is i/o bound?

[marist89]

I use two variants of iostat to see where my system is I/O bound:
iostat -xdMn 5
will sample every 5 seconds in extended format and will translate the devices to device names that you can recognize. Look at the %b column. This tells you how busy your disk is. If %b approaches 90%, you are probably I/O bound for that filesystem.

Also, you can use:
iostat -D sd0 sd1 sdn 5
for all your devices. This will give you a tabular look at the data so you can compare your %b over time...