HP 40 SCSI manual Product Highlights, DDS Technology

QuickSpecs

HP StorageWorks DAT Drives

Product Highlights

DDS Technology	Within the tape market there is a wide range of tape technologies, the question for SMB customers is
	which one to choose. The answer is clear - DDS/DAT continues to be the unit volume leader in the tape
	drive market for small and medium businesses with a current installed base of over 6 million and over
	15 million DAT drives shipped since its introduction in 1989. This remarkable tape technology continues
	to flourish because it meets the needs of the SMB market for cost-effective, reliable backup better than
	any other technology available. Of the 3.5 million backup tape drives shipped in 2003, Gartner
	Dataquest estimates that approximately 50% were DAT drives.
	Unlike AIT, VXA, ADR, SLR, DLT and SDLT, DDS/DAT is based on an open standard format for data
	interchange. The influential DAT manufacturers group presides over this open standard with verification
	processes that ensure compliance. With multiple manufacturers developing and shipping DDS/DAT
	products, customers benefit from increased competition, which leads to better prices, faster development
	and more choice.
	DDS format for DAT is a helical scan format where data is written diagonally across the width of the
	tape. The advantage is that, by allowing subsequent tracks to have different writing angles and to
	overlap, a much greater capacity can be achieved for a given length of tape because no guard bands
	are necessary. The data format also allows for fast location of tracks and data. To achieve this, the
	rotating drum is tilted at a slight angle (6°) from the vertical. The drum has four heads (two write heads
	and two read heads), located at 90° intervals. For each rotation of the drum, two tracks are written. The
	read heads verify the data that has been written (recorded) and the drive rewrites if necessary. The
	straightness with which the track is written to tape is referred to as the linearity of the track and is critical
	in ensuring the data is always recoverable.
	HP has been involved in the design and development of DDS drives since the beginning and applies
	these many years of experience to its current line of DDS products. Not only does an investment in DDS
	technology provide the security of a format with a history of outstanding reliability, the legacy of
	backward compatibility also provides the potential for future expansion without compromising your
	investment in the technology.
	The target market for DDS/DAT continues to be direct-attach backup. In small and medium sized
	businesses cost of ownership, ease of use and a proven history (i.e. low risk) are paramount. DDS
	technology provides the capacity and performance needed in a tape backup solution for workstations
	and entry-level servers.

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