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SCSI Commands
Quantum DLT 8000 Tape System
5-169
5.17 READ POSITION Command (34h
)
The READ POSITION command is used to read a position identifier or SCSI Logical
Block Address (LBA). The LOCATE command uses this identifier to position back to
this same logical position in a high-performance fashion.
Bit
Byte
7
6
5
4
3
2
1
0
0
Operation Code (34h)
1
Logical Unit Number
Rsv’d
TCLP
Long
BT
2 - 8
Reserved
9
Unused
Reserved
Flag
Link
Figure 5–77 READ POSITION Command Descriptor Block — Data Format
Table 5–76 READ POSITION Command Descriptor Block — Field Descriptions
Field Name
Description
TCLP
Total Current Logical Position. When = 1, data returned includes
block, filemark, and setmark position and fits format described in
Section 5.17.2. When = 0, the data takes the SCSI-2 format described
in Section 5.17.1.
This bit indicates the drive returns data specifying the partition, file,
and set number with the current logical position (long form). A TCLP
bit of 0 indicates the device server will return data specifying the first
and last block location with the number of bytes and blocks in the
buffer (short form).
Long
When the Long bit = 1, it indicates the server will return 32 bytes of
data; a value of 0 indicates the device server will return 20 bytes of
data. Both the Long bit and the TCLP bit must both be set to 1 or 0. If
these bits have different values, the drive returns CHECK CONDITION,
ILLEGAL REQUEST.
BT
Block Type. This bit indicates how the position is to be interpreted.
Since the tape drive uses the same logical block regardless of the
setting of this bit, the setting is ignored. The logical block address
values include all recorded objects: blocks and filemarks.
Summary of Contents for DLTtape DLT 8000
Page 1: ...DLTTM 8000 Tape System Product Manual Nov 10 2003 81 60118 06...
Page 5: ...USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT continued...
Page 6: ......
Page 26: ...Table of Contents xxiv Quantum DLT 8000 Tape System...
Page 36: ...About This Manual Quantum DLT 8000 Tape System xxxii...
Page 54: ...General Description and Specifications 1 18 Quantum DLT 8000 Tape System...
Page 102: ......
Page 372: ......
Page 376: ...Appendix A Definition of Vendor Unique Sense Data Information A 4 Quantum DLT 8000 Tape System...
Page 386: ...Appendix C Updating the Firmware C 6 Quantum DLT 8000 Tape System...
Page 396: ...Appendix E Visual Inspection Procedure for DLTtape Cartridges E 8 Quantum DLT 8000 Tape System...
Page 406: ...Appendix G DLT 7000 Emulation Feature G 8 Quantum DLT 8000 Tape System...
Page 407: ......