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a. Parameters for Specifying Alternate Processing Areas for Defective Blocks (Bytes 2 to 9)
The following 4 parameters specify the position and number of spare sectors for
performing defective block alternate allocation processing on the disk media. See Chapter
3, "Data Format" of "OEM Manual VOL. 1, Product Specifications/Installation
Procedures" for details of the IDD's alternate block processing.
•
Track Count/Zone
This parameter specifies spare sectors in assigned units (zone, b, c) for alternating
blocks. The INIT cannot clearly specify this value. The IDD ignores the specification
for this bit. The "Number of Logic Heads" is output by the MODE SENSE and
MODE SENSE EXTENDED commands.
When the notch is active (refer 'notch parameter' on page c), the "Total Number of Tracks"
of the specified zone (No. of ceilings in the zone x No. of logic heads) is reported.
•
Alternate Sector Count/Zone
This parameter specifies the number of sectors per one zone as the number of spare sectors
secured for use as alternate blocks. In the IDD, this parameter indicates the number of
spare sectors secured in each cylinder. The maximum permissible value of this parameter
either the "number of physical sectors per track in the final zone - 1" or "32", whichever is
smaller. It is possible for the INIT to vary this parameter within a range of 0 to the
maximum permissible value. When a value which exceeds the maximum permissible
value is specified, the IDD performs rounding down of the parameter and sets a value equal
to this parameter's maximum permissible value. If the above rounding processing is
performed, a CHECK CONDITION status (RECOVERED ERROR {= 1} / Rounded
parameter [37-00] is reported for that command.
•
Alternate Track Count / Zone
This parameter specifies the area secured for alternate blocks as the number of tracks
per one zone. It is impossible to change this parameter. When a value other than zero
is specified in this field, the IDD performs rounding down processing of this
parameter and always sets this parameter value at zero.
•
Alternate Track Count / Drive
This parameter specifies the area secured for alternate blocks as the number of tracks
per disk drive.
In the IDD, this parameter indicates the number of tracks in the spare area secured as
alternate cylinders. This value is fixed at the number of tracks per 1 cylinder in the
IDD and this parameter cannot be changed from the INIT.
b. Parameters which Specify the Track Format (Bytes 10, 11)
•
Sector Count/Track
This parameter specifies the number of physical sectors per 1 track. In the IDD, the
number of physical sectors in a track is set unilaterally according to the data format
specified by the "Data Block Length" parameter in the block descriptor or the "Data
byte length/Physical sector" parameter in this page descriptor, so this parameter
cannot be changed. The IDD disregards the value specified in this field. This
parameter always indicates the value of zone 0. Also, the "default" value of this
parameter indicates a value which matches the current data format.
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C141-E039-01EN
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