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SPACE 11h
Commands
173
CDB fields:
Space specific status:
If the drive fails to space either from a medium error or from some sort of non-fatal drive error,
CHECK CONDITION status is reported. The sense key will be set to MEDIUM ERROR. Additional
sense depends on the nature of the error. The two most common additional sense code and
qualifiers in this case will be: 1100h (unrecovered read error) and 3B00h (sequential positioning
error).
The drive implements the following priority scheme when a tape position point is encountered:
• If “blank media” is encountered during a space (in other words, the drive attempted to
space on an unformatted tape), the drive behaves as if EOD was at BOM. It will then
Code The Code field indicates what is to be spaced to:
000 Blocks—The number of blocks crossed is dictated by Count.
001 Filemarks—The number of filemarks crossed is dictated by Count.
011 EOD—Space to the end of data in the current active partition.
Count • When spacing over blocks or filemarks this field indicates how many blocks or
marks should be crossed. Spacing is forward (towards EOM) unless Count is
negative (twos complement) when the spacing is towards BOM.
• When spacing to EOD the Count field is ignored.
• When not spacing to EOD, if Count is zero, the
SPACE command is treated as a
null operation. The logical position remains unchanged, and unwritten data is not
flushed to tape.
Parameter Length 0 Explicit block mode is not supported.
Lowest priority Blocks
Filemarks If the drive meets a filemark while spacing to a block
CHECK CONDITION is
reported. The Mark bit in the sense data is set, and the sense key is NO
SENSE. Additional sense is 0001h (filemark encountered). The final
position will be before or after the filemark depending on whether the
space was reverse or forward.
EOD If the drive meets EOD while spacing to a block or mark,
CHECK
CONDITION
is reported. The EOM bit in the sense data is set. The sense
key is BLANK CHECK and additional sense is 0005h (EOD encountered).
BOM If the drive meets BOM while spacing,
CHECK CONDITION is reported. The
EOM bit and Valid bit in the sense data are set to 1 and the information
bytes set to the total number of blocks or filemarks that remain to be
spaced over (in other words, the requested number minus the number that
have been spaced over). The sense key is NO SENSE and additional sense
is 0004h (BOT detected).
Highest priority EOM If the drive meets EOM while spacing,
CHECK CONDITION is reported. The
EOM bit in the sense data is set. The sense key is M
EDIUM ERROR and
additional sense is 0002h (EOP/M detected).