This page describes some of the processes that have contributed to the industry-leading reliability of Hard Disk Drives. All aspects of development and manufacturing are involved in the effort to produce the most reliable products possible. This includes design, component selection, development test, and manufacturing tests. In addition, Hitachi will help system builders with their designs to ensure a reliable environment for Hard Disk Drives.

Reliability has been measured in the industry with Mean Time Between Failure (MTBF), a term or claim that is easy to advertise (a higher number is better), difficult to explain, and nearly impossible to prove or guarantee.

Unlike other hard disk drive performance parameters, reliability cannot be measured until after there has been field experience with the product. Analysis of actual failures is needed for accurate numbers. But Hitachi is able to manage the factors that contribute to high reliability and to predict the results based on:

• Design
• Component selection
• Development test process
• Manufacturing test process
• Customer system design

Terms/acronyms
Since the terms and acronyms used in discussing reliability may vary, a list of common terms and acronyms used by Hitachi is provided below.

High reliability by design
High reliability at Hitachi begins with the design process. As a new disk drive program develops, reliability goals are set, along with access times, data rates, RPM, and cost. Reliability problems and failure modes of past products are studied to help make improvements in the new product. Competitive product data is used to verify Hitachi's position of industry leadership and to show where improvement is needed. Customer feedback is solicited for reliability requirements, product life, and customer environment.

During the development of a new disk drive program, new technologies and manufacturing techniques are tested for performance, quality, yield, and reliability. This testing can be at the component level, subassembly level, or in a prototype disk drive. When development begins on a new product, all of the component, subassembly, and process engineers are involved in the reliability process, helping maintain product quality.

Disk drive features can dramatically affect reliability. Extensive on-the-fly error correction, SMART/PFA, Data Recovery Procedures, error logs, and many other features are designed into the products to maximize product reliability and enhance performance, yield, cost, and time to market.

High reliability through component selection Component, subassembly, and raw-material suppliers are an integral part of the reliability process. Hitachi produces its own disks, MR heads, and many of its logic modules. The quality and reliability of its processes are well-known, and controls and audits are well-documented. Likewise, vendors that supply materials are required to meet Hitachi procurement specifications for process quality and component reliability. A vendor's history of delivering reliable products is a factor determining their selection. Hitachi also has qualification groups that test components and approve suppliers. During the life of a disk drive, component failure analysis data is fed back to the supplier for additional analysis and corrective action.

High reliability from development verification testing Before a new disk drive goes to market, it must pass performance and stress tests at the extreme parameters of the product's specifications. Some of these parameters include acoustics, EMI, ESD, operating environment, power, shock, vibration, temperature, shipping, storage, start/stop, and so on. This testing and improvement continues until the performance meets the specification.

System manufacturers also evaluate engineering-level disk drives in their systems. Reliability Demonstration Tests are run which demonstrate a specified reliability level at the end of the development stage. Passing all of the development verification testing shows that a new product meets performance, quality, and reliability manufacturing targets and is ready for customers.

For Ultrastar server-class disk drives, the reliability engineers develop dynamic stress tests for the logic boards. During the development stage, logic cards are functionally tested beyond their thermal and power specifications. From this testing, a burn-in process is developed to accelerate failures using voltage, thermal, and thermal shock stresses for all production logic boards. Reliability engineers also check the error-logging integrity of the disk drive by forcing opens and short circuits and by assuring the fault is detected and reported correctly. This is known as Maintenance Effectiveness Test (MET).

High reliability from audits and controls Quality control audits alone do not produce reliable disk drives. But they do ensure that processes and procedures are in place to react quickly to problems that may occur. Hitachi is fully ISO 9000-certified for development and manufacturing control. Both short- and long-term Ongoing Reliability Tests (ORTs) are conducted to monitor the initial quality and short- and mid-term reliability of the products. Hitachi also runs an end-of-line quality sampling for selected products. The Outgoing Quality Audit (OQA) simulates an integration test of the product. These tests ensure a repeatable process to assemble and ship a reliably designed product.

High reliability from partnerships with system builders Why is it that customers experience different reliability from the same model disk drive? The design of the computer system, including its hardware, software, diagnostics, supporting service organization, and integration handling can all greatly affect perceived reliability. Technical support is provided for system manufacturers, which can conduct design reviews for disk drive mounting, shock, vibration, cooling, and power. These reviews help end users get the best-possible reliability from the disk drives. Hitachi System Integration Test labs (Asia, USA, Europe) test the drives in existing customer systems and provide "Joint Qualification" support to ensure that the disk drives work well in the customers' systems. The technical support teams provide disk drive handling training packages for customers to help reduce the possibility of damage. Hitachi has the processes, controls, tools, and personnel to deliver the most reliable disk drives in the industry. This partnership can greatly improve the reliability a customer experiences with Hitachi products.

Product description data represents design objectives and is provided for comparative purposes; actual results may vary depending on a variety of factors. Product claims are true as of the date of the first printing. This product data does not constitute a warranty. Questions regarding Hitachi warranty terms or the methodology used to derive this data should be referred to an Hitachi representative. Data subject to change without notice.

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