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SCSI Commands: 22BMODE SELECT
Page
90
3.10.8
Data Compression Control Mode Page (0Fh)
The Data Compression Control mode page specifies whether or not data is
compressed during WRITE commands and whether or not data is decompressed
during READ commands.
Byte
Bits
7 6 5 4 3 2 1 0
0
Reserved Page
Code
(0Fh)
1
Additional Page Length (0Eh)
2
DCE DCC
Reserved
3
DDE RED
Reserved
4
(MSB)
7
Compression Algorithm
(LSB)
8
(MSB)
11
Decompression Algorithm
(LSB)
12
Reserved
13
Reserved
14
Reserved
15
Reserved
3.10.8.1
Data Compression Control Page Field Descriptions
Field Bytes
Bits
Description
Page Code
0
0-5
Always 0Fh, indicating the Data Compression Control Page.
Additional Page
Length
1
Always 0Eh, indicating that 14 parameter bytes follow the Page
Length byte.
DCE
2
7
0 = Data compression is disabled.
1 = Data Compression is Enabled (DCE) (default). The drive
compresses data before writing to tape.
DCC 2
6
Always 1, indicating that the drive is Data Compression Capable
(DCC).
DDE 3
7
0 = Data decompression is disabled. Compressed data is not
decompressed before it is transferred to the host.
1 = Data Decompression is Enabled (DDE) (default). The drive
decompresses compressed data before sending it to the host.
RED 3
5-6
Always 0, indicating that when DDE is 1 and drive is unable to
decompress compressed data from tape, it should return Check
Condition.
Compression
Algorithm
4-7 0 = Data is not compressed before it is written to tape (even if
DCE is 1).
1 = Default compression algorithm (default).
Decompression
Algorithm
8-11
0 = No algorithm is selected.
1 = Default decompression algorithm is used (default).
Reserved
All reserved bits must be 0.
Summary of Contents for LTO 4
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