LogicalDisk|PhysicalDisk\% Disk Time
Reports the percentage of time that the selected disk drive is busy servicing read or write requests. Because this counters data can span more than one sample, and consequently overstate disk utilization, compare this value against % Idle Time for a more accurate picture.
By default this counter cannot exceed 100 percent; however, you can reset the registry to allow System Monitor to display percentages exceeding 100 percent if appropriate. For information about this adjustment and other aspects of performance data collection and reporting, see Performance Objects in Overview of Performance Monitoring in this book.