SCSI Commands
5-76
Quantum DLT 8000 Tape System
MODE SELECT Command (6) / (10) (15h) / (55h) (continued)
Table 5–37 Mode Parameter Header — Field Descriptions
Field Name
Description
Media Type
This field is ignored by the MODE SELECT command.
Buffered Mode
Default = 1. The drive implements immediate reporting on WRITE
commands through its buffered mode. With Buffered Mode set to 1,
the drive reports GOOD status on WRITE commands as soon as the
data block has been transferred to the buffer. If this field = 0, then
the drive does not report GOOD status on WRITE commands until the
data blocks have been written to tape.
When Buffered Mode is not used, the tape drive suffers significant
performance degradation, and possible capacity, depending on tape
format, block size, and compression. When using the 10 or 20 GB
format with compression disabled and block size a multiple of 8
Kbytes, there is no capacity loss.
When writing 10 , 15,20, or 40 GB format with compression enabled
and Buffered Mode disabled, some capacity loss can occur. The block
packing feature is essentially disabled by turning off Buffered Mode.
If Buffered Mode is set to a number greater than 1, the command is
rejected with CHECK CONDITION, sense key of ILLEGAL REQUEST.
Speed
The value of this field specifies the speed at which the drive will
match the transfer rate of the host.
The default setting = 0.
Tape system will attempt to match the drive’s
throughput with the host data throughput.
1 = Used for systems with bus speed below 5.0 MB/second.
2 = Used for systems with bus speeds between 5.0 and 6.0
MB/second
3 = Used for systems with bus speeds of 6.0 MB/second or greater.
NOTE: This information applies only to DLT 8000 format.
Block Descriptor Length
This field specifies the length in bytes of all the block descriptors.
Since the drive only allows one block description, the value must be
either 0 or 8. A value of 0 indicates no block description is included; a
value of 8 indicates a block descriptor is present and precedes the
mode page data. Any other value other than 0 or 8 causes a CHECK
CONDITION status with sense key of ILLEGAL REQUEST to be
returned.
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...
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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...
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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...
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