HP’S DIGITAL LINEAR TAPE LIBRARY ATTACKS MIDRANGE BACK-UP MARKET

The Storage Systems Division of Hewlett-Packard Company in Greeley, Colo. has some catching up to do in the midrange tape drive and library market. The division now claims to lead in optical jukeboxes and 1/2-in. reel-to-reel tape drives. This month, the division rolled out its family of DLT Tape Libraries claiming a number of technology first that it hopes will wrest market share from leader ATL Products Inc. of Anaheim, Calif. (see related story at right).

HP’s new family contains two models that offer storage from 560 gigabytes to 1.9 terabytes. The basic library changer in both family members have some noteworthy technical features. One is a mechanism for ensuring that the drive actually catches the tape leader in the DLT tape cartridge. In the past, a failure mechanism of this class of product was the drive being unable to snag the tape leader, thus requiring repair.

Another technology innovation is in the library gripper used to extract the cartridge from its slot within the library. Many libraries use friction grippers, much as a person would grip the cartridge with a hand. The new library gripper not only friction grips the cartridge, it mates with a hole in the cartridge case to ensure the cartridge does not slip loose.

Light beaming the length of each column in the library detect cartridges partially removed from its storage slot. Upon detecting a cartridge out of place in the library, the gripper positions itself in front of the cartridge and pushes it back into its proper position. This prevents the cartridge from blocking the operation of the library arm accessing cartridges in the library.

In addition, the changer uses a closed loop system for controlling arm movement within the system. An encoded strip on each row on tape cartridge slots provides position information. The feedback allows the library controller to know precisely where vertically in a column the arm and picker are.

A special head cleaner cartridge within the library allows the changer to automatically clean a drive's read/write head if the head indicates it needs cleaning. Furthermore, if a drive should fail, it can be removed and replaced while the library continues to operate.

Other features of the library include a bar code scanner to automatically identify the tape within the library and a bulk loading door that allows a large number of cartridges to be inserted or removed at once. All of these technical features allow the system to offer a 100,000-hour mean-time-between-failure.

The library family comes in three configurations. The base system contains 28 cartridge slots for a native capacity of 560 Gbytes or 1.1 Tbytes compressed. It holds two DLT-4000 tape drives. Quantum Corp. of Milpitas, Calif. builds the drives—the sole source of all DLT drives—to HP's specifications. HP has modified the drive slightly for its library.

The midrange library contains 48 slots offering a native capacity of 960 Gbytes, 1.9 Tbytes compressed. It holds two drives. Both low-end and midrange libraries have a native transfer data rate of 3 Mbytes per second. The high end system has four drives, 48 slots. With the same capacity as the mid-range system, it transfer data at a faster 6 Mbytes/s. The libraries offer a 68-second average access time to data.

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