SCSI Interface Specification
SCSI Communications
AUTOLOADER LTO3 – User Reference Manual Rev. 1.01
TANDBERG DATA
Page 6 0 of 79
SCSI Cable Length
The maximum allowable cable length for a low-voltage differential SCSI bus, including all internal and
external cables, is specified as follows:
If you have more than two devices on the LVD bus, the maximum allowable length is 12 meters
(39 feet).
If you are making a point-to-point connection (target and initiator only), the maximum length is 25
meters (82 feet).
!
!
IMPORTANT
The autoloader and the tape drive are independent SCSI devices on the same
SCSI bus. As a result, when they are connected to the initiator, there are a
minimum of three devices attached to the SCSI bus. Therefore, the maximum
allowable cable length is 12 meters (39 feet).
To determine the cable length of the bus, measure the lengths of all external SCSI cables. Add those
lengths together. To that sum, add 68 centimeters (26.8 inches) for the internal SCSI cable length.
11.1.2 SCSI Terminator Requirements
If the autoloader or the tape drive is the last device on the SCSI bus, you must install an external, wide
LVD terminator on the unused SCSI connector. Do not use internal terminators to terminate the
autoloader or the tape drive. The manufacturer recommends using a Fast 160 SE/LVD multi -mode
terminator.
!
!
IMPORTANT
The manufacturer recommends using active termination. The manufacturers
testing has shown that older passive termination does not provide rising edge
transitions that are fast or clean eno ugh at fast SCSI speeds.
11.2 SCSI Communications
This section provides information about how the autoloader operates as a SCSI device. An application
program uses the SCSI command protocol to control the autoloader and perform the following
operations:
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Move cartridges between the storage locations and the tape drive
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Update and access information stored in the cartridge inventory
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Reserve autoloader elements
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Set various operating parameters
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Inquire about the status of a specific operation
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Prevent cartridges from being imported or exported
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Inquire about the autoloader serial number
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Perform the autoloader self-test
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Upload log parameter data
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Upgrade the autoloader firmware
