User's Manual

DLT2000 SCSI Interface
8-2 DLT2000/DLT2700 Cartridge Tape Subsystem
8.2.2 Initiator/Target Operation
The DLT2000 does not act as an initiator on the SCSI bus. Therefore, the device will
not do any of the following:
• Generate unsolicited interrupts to the host
• Initiate its own SCSI commands
• Assert bus reset
8.2.3 SCSI IDs and Logical Unit Numbers (LUNs)
The DLT2000 with optional medium changer has two logical units. The tape drive will
always appear as LUN 0. The medium changer defaults to appearing as LUN 1, but
may be configured via the MODE SELECT command to any LUN from 1 to 7. Refer to
MODE SELECT section in this chapter.
Unsupported LUNs will be treated as follows: If the LUN specified in the IDENTIFY
message is invalid, the DLT2000 shall accept the Command Descriptor Block (CDB).
There are three cases of what happens next:
1. If the command is INQUIRY, the target shall return the INQUIRY data with the
peripheral qualifier set to 011, indicating that the target will never support the LUN
in question.
2. If the command is REQUEST SENSE, the target shall return sense data. The
sense key shall be ILLEGAL REQUEST, with an additional sense code of
INVALID Logical Unit Number.
3. For any other command, the target shall terminate the command with CHECK
CONDITION status, and generate the above Sense Data.