HP NonStop G-Series - Manual (Page 7)

Chapter One – Introduction
1.5 SCSI Compatibility
The interface for the 5242-2SE tape drive complies with the American National Standard Institute (ANSI)
standard X3T9.2 (SCSI-2). This standard defines the specifications for the Small Computer System
Interface (SCSI). As defined by the ANSI, SCSI is essentially an input/output bus for interconnecting
computers and peripherals.
1.6 DAT72 Format and Compatibility
The 5242-2SE's DAT72 format is an extension of the DDS-3 formats. DAT72 allows 36GB of
uncompressed data to be stored on a DAT72 (170m) tape cartridge. Data compression increases this storage
capacity. A compression ratio of 2:1 raises the capacity to 72GB.
•
The DAT72 format allows compressed data to be stored in a way that maintains the full functionality
of the DDS-3 format and ensures backward compatibility in reading and writing with existing DDS-3
drives.
•
The drive automatically decompresses data even if data compression is inactive.
•
DDS-3 tapes written on a DAT72 tape drive are readable by a DDS-3 tape drive; however, a DAT72
(170m) tape written on DAT72 is not readable on a DDS-3 drive.
•
The DAT72 format uses the same error correction techniques as the DDS-3 format. These incorporate
the error correction techniques used in DAT drives with additional techniques specifically designed to
provide the data integrity required for computer use.
1.7 SCSI Cabling Limitations
Maximum total allowable cable length for a differential SCSI bus is 82 feet (25 meters). This distance must be
measured from the controller to the last device on the bus. Add 12 inches for the internal cable of each unit.
Cables must be 110 ohm twisted pair. If you are using a cable of unknown composition, replace it with one
provided by HP. When ordering, reference one of these part numbers:
519-001W
424360-001 1 meter (3 foot) SCSI Cable 68 pin to 68 pin
519-003W 424361-001 3 meter (10 foot) SCSI Cable 68 pin to 68 pin
519-015W 424362-001 15 meter (50 foot) SCSI Cable 68 pin to 68 pin
519-020W 424917-001 20 meter (67 foot) SCSI Cable 68 pin to 68 pin
519-023W 424363-001 23 meter (77 foot) SCSI Cable 68 pin to 68 pin
Note: SCSI cables for the 5242-2SE are not included. They must be purchased separately.
HP StorageWorks DAT 72 (Model 5242-2SE) User's Guide
3 HP Part Number 528297-003 July 2005