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The spare area in each cylinder is placed at the end of the last track as shown in Figure 3.2. These
spare sectors are located in the end of the track logically, not necessarily located at the end physically
because of track skew or cylinder skew. (Details are explained on Subsection 3.1.3.)
Size can be specified by the MODE SELECT or MODE SELECT EXTENDED command.
The number of spare sectors per cylinder can be specified exceeding 32. The default number of
spare sectors per cylinder is 20 for the MAF3364FC and MAG3182FC and 12 for the
MAG3091FC.
An alternate cylinder is used when spare sectors in a cylinder are used up or 0 is specified as the
number of spare sectors in a cylinder. Several cylinders at the end of the user space are allocated
as alternate cylinders as shown in Figure 3.3.
The number of alternate cylinder is 1.
The user space and the CE space share the alternate cylinders.
3.1.3
Track format
(1)
Physical sector allocation
Figure 3.4 shows the allocation of the physical sectors in a track. The length in bytes of each
physical sector and the number of sectors per track vary depending on the logical data block
length. The unused area (G4) exists at the end of the track in formats with most logical data
block lengths.
Figure 3.2
Spare area in cylinders
Figure 3.3
Alternate cylinder
C141-E078-02EN
SPR1
3 - 5
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