Quantum DLT 2000, Руководство по эксплуатации продукта

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DLT2000 SCSI Interface
DLT2000/DLT2700 Cartridge Tape Subsystem 8-25
8.4.5 LOAD-UNLOAD (1Bh)
Bit
7 6 5 4 3 2 1 0
0 Operation Code(1Bh)
Logical Unit Number Immed
Reserved
Byte
Reserved EOT Re−Ten Load
Unused Reserved Flag
Reserved 1
Reserved
Link
2
3
4
5
Figure 8-10 LOAD-UNLOAD CDB
LOAD-UNLOAD tells the target to load or unload the media in the tape cartridge. If no
cartridge is in the drive, both LOAD and UNLOAD will return a CHECK
CONDITION status with a NOT READY sense key set. If the drive has received an
UNLOAD command with the Immed bit set and then receives another command which
would involve tape motion or TEST UNIT READY, the drive will return a CHECK
CONDITION status with a NOT READY sense key set.
Operation of the Unload version of this command will be different if a media loader is
present.
Two modes of operation are possible when a media loader is attached. If none of the
media loader specific commands has been issued, then the device will operate in the
sequential mode of operation. Once a media loader specific command has been issued,
the sequential mode of operation is disabled and the UNLOAD command becomes a
no-op.
If the device is still in the default sequential mode of operation and an UNLOAD
command is received by the subsystem, the current cartridge will be unloaded and
automatically moved to the magazine slot from which it originated. Then, the cartridge
from the next slot in the magazine, if not empty, is automatically moved from the
magazine into the drive, loaded, and made ready. If the next magazine slot is empty, no
CHECK CONDITION status is created.
When the cartridge is unloaded into magazine slot 6 (the last one), the subsystem does
not cycle back to slot 0. This prevents accidental overwriting of data when using the
subsystem in sequential auto-loading mode. The next cartridge must be selected and
loaded manually, or with a SCSI Move Medium command.