MODE SENSE (6) / (10) Command (1Ah / 5Ah) (continued)
Table 5–56 Data Compression Page — Field Descriptions
Field Name
PS
Page Length
DCE
DCC
DDE
RED
Compression Algorithm
Decompression Algorithm
Description
Parameters Savable. Not supported; must be 0.
The value in this field indicates the number of bytes in the Control
Mode Page being transferred. The value for this byte is 0Eh.
Data Compression Enable. The value returned for this bit depends on
the current WRITE density of the tape drive:
Value
Write Compression is.....
0
Disabled
1
Enabled
Data Compression Capable. The value returned for this bit indicates
whether this tape drive supports data compression
Value
Data Compression is.....
0
Disabled
1
Enabled
Data Decompression Enable. The value returned for this bit indicates
whether data decompression is enabled or not.
Value
Data Decompression is.....
0
Disabled
1
Enabled
Note that when the tape drive reads compressed data from tape, it
automatically decompresses the data before sending it to the
initiator. The value for this bit, therefore, is always 1.
Report Exception on Decompression. The tape drive does not report
exceptions on decompression (boundaries between compressed and
decompressed data). The value returned for RED is 00h.
The value for this field is 10h. This indicates the Lempel-Ziv high
efficiency data compression algorithm.
The value for this field is 10h. This indicates the Lempel-Ziv high
efficiency data decompression algorithm. If EEPROM parameter
EnaRepDCcomp is set, a value of 0 is reported if the last block read is
not decompressed.
Quantum DLT 8000 Tape System
SCSI Commands
5-123