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DLT1/VS80 SCSI Interface Guide
81-81276-01 Rev A01
July 2004
4-15
4.6
LOCATE (2Bh)
Use the LOCATE command for high-speed positioning to the specified block address.
Figure 4-10.
LOCATE (2Bh) Command Descriptor Block — Data Format
When writing, use the READ POSITION command to obtain the block address where particular
blocks of data (for example, a data file) are about to be written. Then use the LOCATE command to
position back to the same logical position for high performance restore operations of particular blocks
of data.
Bit
Byte
7
6
5
4
3
2
1
0
0
Operation Code (2Bh)
1
Logical Unit Number
Reserved
BT
CP
Immed
2
Reserved
3 - 6
(MSB)
Block Address
(LSB)
7
Reserved
8
Partition
9
Unused
Reserved
Flag
Link
Table 4-8.
LOCATE (2Bh) Command Descriptor Block — Field Descriptions
Field Name
Description
LUN
Logical Unit Number. The target ignores this field. Only an IDENTIFY message
can change the LUN.
BT
Block Type. This bit indicates how the Block Address field is interpreted. The tape
drive always returns SCSI Logical Block addresses; that is, setting the BT bit does
not affect the values returned. The first recorded object (block or filemark) is at
address 0, and Block Addresses count both data blocks and filemarks.
CP
Change Partition. Since the drive does not support multiple partitions, this bit must
be 0.
Immed
Immediate. When 1, the drive returns status as soon as the operation starts. When
0, the drive returns status after the operation has completed.
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...
Page 181: ......