Although the extended test has an accuracy rate of 95 percent, the test requires approximately one minute for each gigabyte measured. Today's rapidly increasing areal densities create downtime issues that could impact the decision to run a diagnostic routine on the drive. Returned drives can now be reliably and accurately tested in less than two minutes as part of an RMA reduction process. This will have the added benefit of enabling the customer to discover, within two minutes, whether the drive or another system factor is causing problems-keeping a good drive in the system and minimizing the disruption caused by unnecessarily replacing the drive. For customers of any drive manufacturer implementing NDST, this may result in a reduction in labor costs needed to process RMAs, reduction in overhead inventory required to unnecessarily replace operable hard drives, and less downtime and disruption for the end-user.
End users experiencing system problems can, at times, interpret any issue as a hard drive failure.
Service centers then replace the hard drive, frequently the most expensive component of the system, without examining other possible system issues such as operating system or file system corruption, software incompatibilities or other system components. This is disruptive to the user, causing loss of productivity and the possibility of lost data if the drive's contents were not backed up by the end-user. The genesis for DST was to solve the problem of retiring good drives from service because of diagnostics that were either inadequate or not readily available. Before DST was included in the firmware of each drive, a host software diagnostic application was required to fully test the hard drive. This software was not always readily available and relied on standard read and write commands to diagnose the drive.