3.1.2Alternate spare area
The alternate spare area is provided in the last track of each primary cylinder in the user space, and in the last track of the cylinder and the alternate cylinder.
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 command.
The number of spare sectors per cylinder can be specified exceeding 32. The default value of number of 9space sectors per cylinder is 20.
Figure 3.2 Spare area in cylinders
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.
Figure 3.3 Alternate cylinder
Note:
Zero cannot be specified for both the number of spare sectors in each cylinder and the number of alternate cylinders.
3 - 5 |
