When a Disk Drive Fails

UltraTrak100 TX4 and UltraTrak100 TX8 User Manual

A non-fault tolerant array goes "offline" when a drive is removed or fails. Since the array is not fault tolerant, the data stored in the array is no longer accessible. If the drive was removed, then it should be replaced to restore accessibility to the array. If the drive failed, then the entire array must be deleted and re-initialized since all data is considered lost.

REBUILDING/SYNCHRONIZING FAULT TOLERANT ARRAYS

Though a critical array can continue storage operations, it no longer offers fault tolerance and should be addressed as soon as possible by replacing the missing or failed drive(s).

Rebuild takes a replacement drive, assigns it to the array, and then writes the redundancy data to it. Once the rebuild process is complete, the array status is upgraded from “critical” to “functional” and fault tolerance is restored.

Synchronization is a preventative maintenance measure used to avoid problems with data integrity. Synchronizing simply recalculates redundant data (similar to the rebuild process) and matches the data on the drive(s).

To synchronize the array, go to the Configuration menu and select Configure Array; then select Advance Features and choose Synchronize Array.

The UltraTrak100 provides both audible and visual indicators alerting you of a drive failure. The following occur when a disk drive fails or goes offline:

•Continuously produces short beeps every two seconds when a drive fails.

•Continuously produces long beeps every 15 seconds when a drive is offline.

•The Array LED on the front panel is yellow.

•The disk drive Status LED (inside front panel door) is red.

•The LCD displays a status message about the failure.

REPLACING A DISK DRIVE MODULE

UltraTrak100 disk drive modules should not be removed unless it has been determined that a drive in the array has failed.

Generally, a disk drive that is a member of a fault tolerant array may be replaced at any time without affecting the availability of data to the system. Depending on the RAID type, drive removed, and type of access, performance may be reduced until the drive is replaced.

Disk drives may be replaced while UltraTrak100 is running; special circuitry is designed into the UltraTrak100 that protects the components and notifies the processor.

Only a failed drive should be removed from the array. Removing any other drive may cause the array to become unavailable. The replacement drive must be of equal capacity or larger than the failed drive.

In arrays where a hot spare is already installed, the hot spare automatically replaces the failed drive. When the failed drive is replaced, the new drive becomes the new hot spare.