Disk activity resets the hard drive timer delaying hard drive spin down (306613)

SYMPTOMS

Your machine appears to have been sitting idle for more time than the "Turn off hard disk" setting in the "Power Options Properties", and the hard drive has not spun down.

CAUSE

Any Disk Activity will reset the spin down timer back to the "Turn off Hard Disks" setting, and begin the countdown again.

For example, with the setting "After 5 Minutes", if no disk activity occurs for 4 minutes, and an application reads from disk, the timer will reset and the machine will wait an additional 5 minutes before spinning down. Since it takes a few seconds for the drive to spin up, this feature of the operating system is designed to delay spinning down the hard drive until no activity occurs for a period of time, so the system does not spin down the drive needlessly.

RESOLUTION

The following actions can minimize, or eliminate, this system behavior:

When you are not going to use them, close any applications that cause disk activity.
Change scheduled tasks to occur less frequently (see the "More Information" section for a specific item pertaining to Windows Millennium Edition).
Reduce or increase timer settings in applications to prevent disk activity.

WORKAROUND

The configuration of operating components may prevent hard drive spin down in a desirable amount of time. To increase the opportunity for the hard drive to spin down, set the "Turn Off Hard Disks" setting to "After 3 minutes".

MORE INFORMATION

It is obvious that all applications may cause disk activity; however, the following components are common sources of disk activity unknown to the user.

When the monitor turns off according to the power management settings, disk activity occurs to run the code to turn off the monitor. With the "Turn off Monitor" and "Turn off Hard Disks" settings both at 5 minutes, the monitor will turn off in 5 minutes, and the hard drive will spin down 5 minutes later.
Windows Millennium Edition ships with a service named PC Health, which is configured to run every 10 minutes in Task Scheduler. Once it completes and the machine has been rebooted, it will be set to run every 6 hours. Any task that is scheduled to run as often as 10 minutes will cause disk activity; the effect is that the hard drive will not spin down.