![background image](http://html1.mh-extra.com/html/quantum/dlttape-dlt-4000/dlttape-dlt-4000_product-manual_3688580165.webp)
SCSI Commands
Quantum DLT 4000 Tape Drive
5-65
MODE SELECT (6) / (10) Command (15h) / (55h) (continued)
Table 5–34 MODE SELECT 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 writing 2.6 or 6.0 GB formats
and block size that is a multiple of 4 Kbytes, there is no capacity loss.
Likewise, 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 or 20 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 tape drive supports only its default speed.
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 4000
Page 1: ...DLT 4000 Tape Drive Product Manual November 10 2003 81 60043 04 ...
Page 5: ...USER MANUAL STATEMENTS FOR CLASS B EQUIPMENT continued ...
Page 6: ......
Page 24: ...About This Manual Quantum DLT 4000 Tape Drive xxiv ...
Page 62: ...Hardware Implementation 2 28 Quantum DLT 4000 Tape Drive ...
Page 100: ...Messages 4 12 Quantum DLT 4000 Tape Drive ...
Page 264: ...SCSI Commands 5 164 Quantum DLT 4000 Tape Drive ...
Page 274: ...Appendix B EEPROM Resident Bugcheck and Event Logs B 6 Quantum DLT 4000 Tape System ...
Page 280: ...Appendix C Updating the Firmware C 6 Quantum DLT 4000 Tape Drive ...
Page 298: ...Index Index 6 Quantum DLT4000 Tape Drive ...
Page 299: ......