Compaq ProLiant 1000 Drive technology overview - Page 6

Enterprise drives are designed for unlimited I/O workloads, that is, for continuous I/O activity. Midline and Entry drives are designed for low work I/O workloads. If any doubt exists about the expected workload, and if reliability is a priority, then Enterprise drives should be used. Drives are subject to mechanical problems created by shock, vibration, environmental extremes, and thermal effects. These problems may degrade performance or reliability (for example by displacing the read head from the data track). They may cause data loss, or even cause catastrophic failure of the drive. Of the three categories of HP drives, Enterprise drives are the most resistant to vibration effects. Midline drives have a lower tolerance to vibration than Enterprise drives. Both HP Enterprise and Midline drives have internal sensors that detect operational/rotational vibration and reduce the performance impact from system, drive-to-drive, and environmental vibrations. Entry class drives will exhibit degraded performance in high vibration environments. Multiple drives in a single enclosure may interact to create coupled vibration problems. This can occur when using Entry or Midline drives with Enterprise class I/O workloads. In fact, Entry drives are not supported in some external storage solutions due to the higher levels of system and drive-to-drive vibrations. Temperature is a major factor influencing reliability and is usually best managed by controlling the operating environment. Higher operating temperatures will negatively affect disk drive relaibility. Drive qualification process HP employs best-in-class qualification and quality control processes to ensure that the disk drives it ships remain reliable, meet customer requirements, and integrate seamlessly into HP server and storage systems. The HP processes also ensure continuous improvement in both current and future products and processes. The qualification process consists of four specific steps: 1. Selection evaluation 2. Development verification 3. Supplier production qualification 4. Continuous improvement/performance monitoring HP development engineers work closely with disk drive suppliers to execute a comprehensive set of approximately 50 different procedures and specifications that determine the testing and metrics that a candidate drive design must satisfy. Approximately 1000 unique hard disk drives are typically used to evaluate a product family during the selection evaluation and development verification steps, and approximately 2 million drive test hours transpire. The supplier production qualification phase includes a thorough analysis of the supplier's capabilities, focused on validating supplier process capability and process controls, and on measured product quality. The analysis includes extensive review of the supplier's process controls, closed-loop corrective action processes, and overall quality control system. The final stage of the supplier production qualification includes a comprehensive analysis of the product's quality performance through the HP configuration pilot. Disk drive products that pass the extensive HP qualification process proceed into the HP continuous improvement/disk drive performance monitoring phase during volume production. This phase includes three main areas of focus:  Validate that volume production is in process control  Measure, analyze, and react to product quality data  Deliver continuous product improvements HP and the disk drive suppliers work as a team during the volume production phase of a product. The team monitors the performance of each product through quality control methods at the supplier's 6