48 Tables of Switch Settings
DC Control by
Density
This enables device-based control of data compression for SUN and Exabyte drivers,
and also for Exabyte drives, which control data compression through the Density
Code. In other words, depending on the device filename or device Minor Numbers,
the driver sends a Density Code of 0 or 3 on device open.
3
Data compression on writes is enabled by
MODE SELECT
Density Code (byte 0 of
the Mode Block Descriptor) of 3, and disabled by a Density Code of 0.
7
The Density Code indicates drive/tape density and has no effect on data
compression.
Default Fixed
Mode
Some applications (particularly PC-based), designed originally for use with QIC
drives, expect a SCSI fixed block length of 1 KB. SCSI states that they should
configure this through
MODE SELECT
, but some applications simply assume that the
drive is pre-configured for 1KB fixed-size blocks.
3
Defaults to fixed block mode with block size set to 1 KB (1024 bytes).
7
The default block size is 0 (variable block mode).
EW-EOM on
Read Error
3
The EOM bit is set for read errors resulting from read commands meeting the
EW-EOM mark.
7
The EOM bit is only set if the tape is at physical EOP/M.
Fixed 512 Bytes
Some applications (particularly PC-based), designed originally for use with QIC
drives, expect a SCSI fixed block length of 512 bytes. SCSI states that they should
configure this through
MODE SELECT
, but some applications simply assume that the
drive is pre-configured for 512-byte fixed-size blocks.
3
Defaults to fixed block mode with block size set to 512 bytes.
7
Default block size depends on the Fixed mode setting.
Forced Eject
3
The Forced-Eject function is enabled.
7
The Forced-Eject function is disabled.
Full Reset
3
The drive performs a
firm
reset initialization in the event of a SCSI reset, or on
receipt of a
BUS DEVICE RESET
message.
7
The drive performs a
soft
reset initialization in the event of a SCSI reset, or on
receipt of a
BUS DEVICE RESET
message.
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