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Chapter 4: SCSI Commands
4-108
July 2004
81-81276-01 Rev A01
4.19 RESERVE UNIT (16h)
The RESERVE UNIT command reserves the specified tape drive for the exclusive use of the
requesting initiator or for another specified SCSI device. The reservation remains in effect until one of
the following conditions occurs:
•
The initiator that made the reservation sends another RESERVE UNIT command.
•
The same initiator releases the tape drive with the RELEASE UNIT command.
•
The tape drive receives a BUS DEVICE RESET message from any initiator.
•
A hard reset occurs.
The occurrence of the last two conditions is indicated by the tape drive returning a CHECK
CONDITION status with a Sense Key of UNIT ATTENTION on the next command following the
condition. It is not an error to issue a RESERVE UNIT command to a tape drive that is currently
reserved by the requesting initiator.
Figure 4-70.
RESERVE UNIT (16h) Command Descriptor Block — Data Format
If another initiator has previously reserved the logical unit, the target returns a RESERVATION
CONFLICT status.
If, after the tape drive has honored the reservation, any other initiator attempts to perform any
command except INQUIRY, REQUEST SENSE, or RELEASE UNIT, the tape drive rejects the
command with a RESERVATION CONFLICT status. A reserved logical unit ignores a RELEASE
UNIT command issued by another initiator.
Bit
Byte
7
6
5
4
3
2
1
0
0
Operation Code (16h)
1
Logical Unit Number
3rd Pty
Third Party Device ID
Rsv’d
2 - 4
Reserved
5
Unused
Reserved
Flag
Link
Summary of Contents for DLTtape DLT1
Page 1: ...DLT1 VS80 SCSI Interface Guide...
Page 6: ...DLT1 VS80 SCSI Interface Guide vi July 2004 81 81276 01 Rev A01 Notes...
Page 12: ...Table of Contents xii July 2004 81 81276 01 Rev A01 Notes...
Page 16: ...List of Figures xiv July 2004 81 81276 01 Rev A01 Notes...
Page 20: ...List of Tables xviii July 2004 81 81276 01 Rev A01 Notes...
Page 24: ...Chapter 1 Introduction 1 4 July 2004 81 81276 01 Rev A01 Notes...
Page 32: ...Chapter 2 General SCSI Bus Operation 2 8 July 2004 81 81276 01 Rev A01 Notes...
Page 42: ...Chapter 3 SCSI Messages 3 10 July 2004 81 81276 01 Rev A01 Notes...
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