Quantum DLT 4700, Product Manual

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DLT4000/DLT4500/DLT4700 Cartridge Tape Subsystem -101
.4 17 RELEASE UNIT (17h)
Bit
6 5 3 2 0
0 Operation Code (17h)
1 Logical Unit Number
3rdPty
Third Party Device ID Rsvd
2 Reserved
Byte 3 Reserved
4 Reserved
5 Unused Reserved Flag Link
Figure 8-68 RELEASE UNIT CDB
RELEASE UNIT releases the drive if it is currently reserved by the requesting
initiator.
It is not an error to attempt to release the drive if it is not currently reserved by the
requesting initiator. However, if it reserved by another initiator, the drive is not
released.
3rdPty
The third-party release option for RELEASE UNIT allows an initiator to release a
logical unit that was previously reserved using the third-party reservation option. If
the third-party (3rdPty) bit is zero, then the third-party release option is not requested.
If the 3rdPty bit is one, the drive is released if it was originally reserved by the same
initiator using the third-party reservation option, and if the device is the same SCSI
device that was specified in the third-party device ID field.
8.4.17.1 Medium Changer Considerations
The optional Element reservation feature defined for Medium Changer devices in
SCSI-2 is not supported, so the RELEASE command is defined the same as for the
tape drive: Only the whole loader unit can be released. Reserve/release of the Loader
and Drive LUNs are handled independently.