Average seconds per operation is a good indicator of disk activity and health. An I/O is expected to take under .015 ms on ...

Average seconds per operation is a good indicator of disk activity and health.  An I/O is expected to take under .015 ms on a health disk sub-system.  Values greater than this, especially if the Idle time is high or the disk I/O rate is low, suggest the disk is having trouble reading or writing.  Use any of the suggested Disk diagnostic tests if the later situation exists.