Disk Failure Diagnostics

Disk reliability problems can vary in severity. Minor problems can cause seemingly random application failures. For example, if a user connects a new camera and the operating system fails to load the driver, disk corruption may be causing the problem. More severe problems can result in the total loss of data stored on the hard disk.

Windows can eliminate much of the impact of a disk failure by detecting disk problems proactively, before total failure occurs. Hard disks often show warning signs before failure, but earlier Windows operating systems did not record the warning signs. Windows now checks for evidence that a hard disk is beginning to fail and warns the user or the Support Center of the problem. The IT department can then back up the data and replace the hard disk before the problem becomes an emergency. For administrators, Windows acts as a guide through the process of backing up their data so that they can replace the drive without data loss.

Most new hard disks include Self-Monitoring Analysis and Reporting Technology (SMART) and Disk Self Tests (DSTs). SMART monitors the health of the disk using a set of degradable attributes, such as head-flying height and bad block reallocation count. DSTs actively check for failures by performing read, write, and servo tests.

Windows queries for SMART status on an hourly basis and regularly schedules DSTs. If Windows detects impending disk failure, Windows can start disk diagnostics to guide the user or IT professionals through the process of backing up the data and replacing the disk before total failure occurs. Windows can also detect problems related to a dirty or scratched CD or DVD and instruct the user to clean the media.

You can configure disk diagnostics using two Group Policy settings. Both are located in Computer Configuration\Policies\Administrative Templates\System\Troubleshooting And Diagnostics\Disk Diagnostic.

• Disk Diagnostic: Configure Execution Level Use this policy to enable or disable disk diagnostic warnings. Disabling this policy does not disable disk diagnostics; it simply blocks disk diagnostics from displaying a message to the user and taking any corrective action. If you have configured a monitoring infrastructure to collect disk diagnostic events recorded to the event log and prefer to manually respond to events, you can disable this policy.
• Disk Diagnostic: Configure Custom Alert Text Enable this property to define custom alert text (up to 512 characters) in the disk diagnostic message that appears when a disk reports a SMART fault.

For disk diagnostics to work, the Diagnostic Policy Service must be running. Note that disk diagnostics cannot detect all impending failures. Additionally, because SMART attribute definitions are vendor specific, different vendor implementations can vary. SMART will not function if hard disks are attached to a hardware redundant array of independent disks (RAID) controller.

Note Many hardware vendors use SMART failures as a warranty replacement indicator.