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6.Command Specification
SPACE
Note d: The drive will only report that a Set-mark has been detected while spacing over blocks or File marks, if it has
been configured through MODE SELECT to Report Set-marks. Otherwise, the drive will continue the space
operation and the presence of the Set-mark will be transparent to the Host.
Note e: The tape is positioned such that a subsequent WRITE would append data after the last entity that has been
written to the tape before EOD.
Note f: The tape is physically positioned at BOM/P.
Note g: EOM is only reported when the physical EOM/P is encountered. The tape is physically positioned at EOM/P.
6.26.1. CHECK CONDITION
NO SENSE: If a File-mark occurs while spacing over blocks, the File-mark and Valid bits in extended sense are set
to one. The Information bytes are set to the difference (residue) between the requested count and the actual number
of blocks spaced over (not including the mark).
If a Save Set Mark occurs while spacing over blocks or File-marks, nothing is reported unless the SDX-450V has
been configured through MODE SELECT to Report Save Set Marks.
If the Report Save-Set Marks configuration is enabled and a Save-Set Mark occurs while spacing over blocks or File
marks, the Valid bit and the Additional Sense keys in the Returned Sense data are set to indicate that a Save-Set
Mark has been encountered. The information bytes are set to the difference (residue) in the requested count and the
actual number of blocks or Save-Set Marks spaced over (not including the detected Save-Set Mark).
If End-of-Data is detected while spacing over blocks or marks, the Valid bit and the Additional Sense Keys in the
Returned Sense Data are set to indicate that an EOD mark has been encountered. The Information bytes are set to
the difference (residue) in the requested count and the actual number of blocks or marks spaced over.
If BOT is detected while spacing over blocks or marks in the reverse direction, the EOM bit is set in extended sense.
The Valid bit is set to one and the Information bytes to the difference (residue) between the requested count and the
actual number of blocks or File marks spaced over.
6.26.2. Sony SDX-450V Unique Implementation for SPACE
6.26.2.1. Super High Speed Search
The Sony SDX-450V will automatically accelerate the fast search operation by using physical position map
information in MIC, while long distance space operation. The fast search speed is 75 times faster than nominal, and
the accelerated search speed is 120 times faster than nominal. The nominal search speed is 450 Mbytes/sec in AIT2
Tape, 225 Mbytes/sec in AIT1 Tape. The Sony SDX-450V manage the physical position map information in MIC
automatically, without special SCSI commands or hardware settings.
6.26.2.2. Data Buffer Management
The drive's buffer holds up to 5 groups worth of data (since the data buffer is 8 Mbytes) in AIT2 mode. Therefore, a
single record (less than 8 Mbytes in length) might be read and then backspaced over repeatedly without the tape
moving since once the record is within the buffer, no further information is required from the tape.
6-98
SONY AIT-1 Turbo drive SDX-450V series Ver.1.0
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