User's Manual

Chapter 5 SCSI Interface
Page 44 STT20000A Product Manual
Parameters that control data compression
A
D
ata
C
ompression
E
nable (DCE) bit of one indicates that data compression is to
be enabled. When this bit is set, data sent to the Drive by the Host shall be
processed using the ALDC compression algorithm prior to being written to the
medium. A DCE bit of zero indicates that data compression is disabled.
A
D
ata
C
ompression
C
apable (DCC) bit of one indicates the Drive support data
compression and shall compress data, using the ALDC algorithm, prior to writing to
the medium when DCE bit is one. A DCC bit of zero indicates the Drive does not
support data compression. This is a non-changeable field.
A
D
ata
D
ecompression
E
nable (DDE) bit of one indicates that data decompression
is to be enabled. A DDE bit of zero indicates data decompression is disabled.
Normally DDE is always set, on tape drives that support hardware data
compression.
Compression Algorithm defines the data compression algorithm used by the Drive.
The ALDC compression algorithm value is 0001h. This is a non-changeable field.
Decompression Algorithm defines the data decompression algorithm used by the
Drive. The ALDC decompression algorithm value is 0001h. This is a non-
changeable field.