Disk drive vintage and its effect on reliability

Field failure data for 3 disk drive families from 3 drive manufacturers is analyzed. The analyses illustrate the effects of design and manufacturing process improvements implemented throughout the drive's production life on the reliability of disk drives. Also, the resultant effect of convolution of different shipment volumes and different vintage drives reliability is studied. Two drive families show distinct reliability differences between drive vintages. The newer vintage drives are more reliable than the older vintage drives. One interesting observation is the ratio of average failure rate during the first three or four months of production to the average failure rate later in time when failure rate has stabilized. This ratio is observed to be between 2 and 3. One drive family, on the other hand, showed almost no difference in the reliability between vintages because of a dominant failure mechanism that was unaffected by most of the design and manufacturing process changes implemented. Also, if the shipment volumes are high in the beginning period of the drive shipments the overall reliability of the field population may be lower due to a high contribution of the early vintage drives with higher failure rates.