Quantum DLT 8000 Product Manual page 220

SCSI Commands
MODE SELECT Command (6) / (10) (15h) / (55h) (continued)
Table 5–37 Mode Parameter Header — Field Descriptions
Field Name
Media Type
Buffered Mode
Speed
Block Descriptor Length
5-76
Description
This field is ignored by the MODE SELECT command.
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.
The value of this field specifies the speed at which the drive will
match the transfer rate of the host.
The default setting = 0.
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.
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.
Quantum DLT 8000 Tape System
Tape system will attempt to match the drive's