Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications page 86

Command Specifications
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Block descriptor length
This field indicates the length (block count) of the "Block descriptor" which follows the header
(not including the length of the "Page descriptor"). It is possible to define only 1 "Block
descriptor" to the IDD, and either X '00' or X '08' must be specified in this field. When X '00' is
specified in this field, it indicates that the "Block descriptor" is not included in the parameter list
transferred from the INIT and the "Page descriptor" follows immediately after the "Header."
b. Block descriptor
The logical attributes of the data format on the disk media are described in the 8-byte long "Block
descriptor."
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Data block count
This field specifies the total number of logical data blocks (the block length is specified in "Data
block length) allocated in the user space on the disk media. The maximum logical block
address is a value with 1 subtracted from the value in this field.
If only the "Block descriptor" in this command is changed accessible data block count can be
limited without formatting if "Data block count" value is within a "Cylinder count" value of
page 4.
If zero is specified for the "Data block count," or when the block descriptor is not specified, the
IDD retains its current capacity, if the block size or alternate sector count has not changed. If
the "Data block count" is set to zero and the Data block size or alternate sector count has
changed, the IDD shall set to its maximum capacity when new block size or alternate sector
count to be effect.
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Data block length
This field specifies the byte length of a logical data block on the disk media.
The logical data block length and physical data block length are the same in the IDD.
The data block length can be specified at 512 to 528 bytes (4-byte boundary).
If less than 512 bytes is specified in this field, the IDD performs rounding processing (there is a
rounding processing report), setting the data block length at 512 bytes. If more than 528 bytes
is specified, rounding processing is performed (there is a rounding processing report), setting
the data block length at 528 bytes. If the number except the multiple of 4 is specified within this
range, the number is rounded up at the multiple of 4 that is closest to the specified number.
(Rounding processing is reported.)
If zero is specified in this field, the value specified in bytes 12 and 13 (Data byte length/sector)
of Page 3 (Format Parameter) is set. At that time, if Page 3 is not specified at the same time, the
current value in Page 3 is used.
If the value set in this field differs from the value specified in bytes 12 and 13 (Data byte
length/sector) of Page 3 (Format Parameter), the data block length in the block descriptor is set.
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