Compaq 108164-003 - ProLiant - 800 Technology Brief page 3

ECG036/1297
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I N T R O D U C T I O N
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An efficient, reliable, and cost-effective solution for backup of critical data is a requirement
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for companies of any size. Compaq has a strong record of providing industry-standard storage
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solutions to fit a variety of customer needs. Not everyone requires hundreds of gigabytes of
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storage or can afford the more expensive backup solutions designed for customers with much
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heavier backup loads. Increasingly, small and mid-size businesses use departmental servers,
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such as the Compaq ProLiant 1200, ProLiant 1600, or ProLiant 2500 servers with storage
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requirements of 24 GB or less. To meet the needs of mid-size businesses, Compaq has an
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affordable line of DAT drives that use the DDS recording format and provide fast, reliable
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data storage.
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This brief explains DAT and DDS technologies and the performance improvements of DDS-3
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over DDS-2. This paper also explains why DDS-3 provides low total cost of ownership.
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Finally, this brief describes the Compaq 12/24 GB DAT Drive with DDS-3 format, including
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the backup software that it supports.
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B A C K G R O U N D I N F O R M A T I O N
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DAT technology was initially developed for consumer audio recording. DDS is a data storage
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format that was developed from DAT to provide high-density, high-quality, reliable computer
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data backups. The physical media (drive and tapes) are referred to as DAT, while the
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recording format is referred to as DDS.
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What is DAT?
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DAT is a digital recording technology that uses 3.81mm (0.15-inch) wide tape in a helical
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scan read/write recorder. Unlike other tape technologies that only have tape movement,
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helical scan has both tape and head movement. With tape and head movement, the tape speed
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is slower, incurring less tape wear and maintaining better control of the tape as it moves
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through the tape path. The read and write heads in a drive that uses helical scan are attached to
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a rotating transport drum, which sits at a 6-degree angle to the tape media (Figure 1). Data is
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recorded in diagonal stripes from bottom to top on the tape, which moves in the same direction
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as the drum.
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Figure 1: DAT helical scan recording.