Tracking if disk is busy

[Matt Ruzicka]

We've got a couple servers that appear to have particularly busy disks and 
I was trying to determine if there is a way to more easily poll this data 
for tracking.

I'm not sure if this is one of those can't see the forest for the trees 
issues or not, but the only means that I am familiar with to see the 
percentage of time the disk is busy is to run 'systat -vmstat'.  I was 
hoping for something more concise that I could run periodically and maybe 
even graph (realizing that watching this might well distort the results).

It appears that iostat on Solaris gives this information, but I can't seem 
to mimic this functionality with FreeBSD.

Are there other ways in FreeBSD to pull the percentage of time the disk is 
busy?

Thanks.

Matt Ruzicka - Systems Administrator
Front Range Internet, Inc.
matt at frii.net - (970) 212-0728