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5-142 Quantum DLT 7000 Tape System
5.17 RELEASE UNIT COMMAND (17h)
The RELEASE UNIT command releases the drive if it is currently reserved by the
requesting initiator. It is not an error to release the tape drive if it is not
currently reserved by the requesting initiator. If the tape drive is reserved by
another initiator, however, it is not released; the tape drive is only released from
the initiator that issued the RELEASE command.
Bit
Byte
7 6 5 4 3 2 1 0
0 Operation Code (17h)
1 Logical Unit Number 3rd Pty Third Party Device ID Rsv’d
2 - 4 Reserved
5 Unused Reserved Flag Link
Figure 5–71 RELEASE UNIT Command Descriptor Block - Data Format
Table 5–68 RELEASE UNIT Command Data - Field Descriptions
Field Name Description
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 this bit is 0, then the third-party release option is not requested. If this bit is set
to 1, the drive is released if it was originally reserved by the same initiator using
the third-party reservation option and if the tape drive is the same SCSI device
specified in the Third Party Device ID field.
Third Party
Device ID
Required if the 3rdPty bit is 1. This field specifies the SCSI ID of the initiator
whose third party reservation is being released. This field must be set if the
initiator of the original third party RESERVE is the source of the RELEASE.