I've got a counter log running that samples the server every 5 minutes for a 24 hour period. I'm asking if the number produced in the report is an average number. For example the % disk time number is 15.401. Does this mean the average amount of time the disk was busy over that 24 hour period was 15%?

We have another server and the % disk time number is 160.234%. How could a number like that be produced? I thought that once it reached a 100% that's it.

I'm using the Perfmon wizard that I downloaded off of MS's site to create the counter log.

You can go over 100% busy on a RAID array, but not usually a single disk. Also, are these Logical Disk or Physical Disk counters? One last thing - one snapshot every 5 minutes is a pretty large gap, so is there any reason you didn't go with 5 seconds over 24 hours and a 250 - 300MB log file?

It's a physical disk counter. And, I started out sampling every 30 seconds but I don't see much difference in the numbers, between 5 minutes and 30 seconds. Now can you tell me if the number in the report is an average number?

Also, that is a Raid5 setup for the disks that are running at a 160%.

The disk time counter number is an average, yes. And the reason you see 160% is precisely because it's a physical disk counter - the OS knows via the driver that there are 3 physical disks there, so I would expect that 160% busy on a 3 disk RAID5 is approximately 50-60% busy across all 3 disks.