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Page Code The Page Code identifies the type of MODE SELECT page being
transferred. A value of 0Fh identifies this as the Data Compression
page.
Page Length The Page Length field indicates the number of bytes in the Data
Compression page that follow this byte. The valid value for this byte
is 0Eh.
DCE Data Compression Enable. This bit specifies whether the tape drive
should enable or disable data compression. When set to 1, the drive
starts in compressed format.
DCC Data Compression Capable. This bit is used by the MODE SENSE
command to indicate that the tape drive supports data compression.
DDE Data Decompression Enable. Must be set to 1. When the tape drive
reads compressed data from tape, it automatically decompresses
the data before sending it to the initiator. Data compression must
always be enabled.
RED Report Exception on Decompression. The tape drive does not report
exceptions on decompression (boundaries between compressed
and uncompressed data). The RED field must be 00h.
Compression
Algorithm The Compression Algorithm field indicates which compression
algorithm the tape drive will use to process data from the initiator
when the DCE bit (byte 02, bit 7) is set to 1. The only value currently
supported for this field is 10h.
127( Specifying a value other than 10h for this field causes the
tape drive to return CHECK CONDITION status, sense key
set to ILLEGAL REQUEST. However, if EEPROM
parameter EnaRepDecomp is set, the parameter in this
field is ignored and no CHECK CONDITION status is
returned.
Decompression
Algorithm The Decompression Algorithm field indicates which decompression
algorithm the tape drive will use when decompressing data on the
tape. The only value currently supported is 10h.
127( Specifying a value other than 10h for this field causes the
tape drive to return CHECK CONDITION status, sense key
set to ILLEGAL REQUEST.
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