Fujitsu MAN3735 Manuel D’Utilisation
C141-E124-01EN
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1.8
Data Block Addressing
1.8.1
Definition of data space
The IDD manages the data storage area on the disk drive in the following 2 types of data space.
x User space: user data storage area
x System space: IDD exclusive area
x System space: IDD exclusive area
Within these 2 areas, the user can clearly access the user space. The data format and defect
management methods in this space are the same and it is possible to access this space by logical
data block addressing described in Section 1.8.2. System space is accessed by the IDD internally
when the power is switched on or during processing of specific commands, but it cannot be
accessed directly by the user.
management methods in this space are the same and it is possible to access this space by logical
data block addressing described in Section 1.8.2. System space is accessed by the IDD internally
when the power is switched on or during processing of specific commands, but it cannot be
accessed directly by the user.
Figure 1.5 shows the data space configuration on the disk drive. The number of cylinders allocated
to user space can be specified by the user (MODE SELECT or MODE SELECT EXTENDED
command).
to user space can be specified by the user (MODE SELECT or MODE SELECT EXTENDED
command).
A spare sector area (alternate area) for use as alternate sectors for defective sectors is allocated in
the user space. The IDD manages defects for each cell, which consists of several cylinders (see
Figure 1.5). The user can allocate the number of sectors in the last track of each cell and the
number of cylinders in the user space (alternate use cylinders) as the alternate area (by the MODE
SELECT or MODE SELECT EXTENDED command). Only one cylinder can be specified as an
alternate cylinder for the IDD.
the user space. The IDD manages defects for each cell, which consists of several cylinders (see
Figure 1.5). The user can allocate the number of sectors in the last track of each cell and the
number of cylinders in the user space (alternate use cylinders) as the alternate area (by the MODE
SELECT or MODE SELECT EXTENDED command). Only one cylinder can be specified as an
alternate cylinder for the IDD.
Alternate data blocks are allocated in defect sector units for defective sectors on the disk media
through internal IDD defect management. Through this defect management, the INIT can access
all the logical data blocks in the user space as if they were error free.
through internal IDD defect management. Through this defect management, the INIT can access
all the logical data blocks in the user space as if they were error free.
For details concerning the data format on the disk media (cylinder configuration, track format and
sector format) and details concerning defect management techniques and alternate block allocation
techniques, Chapter 3 “Data Format” in the “Product Manual.” For an outline of defect
management techniques, see “Disk Media Management” in Chapter 6 of this manual.
sector format) and details concerning defect management techniques and alternate block allocation
techniques, Chapter 3 “Data Format” in the “Product Manual.” For an outline of defect
management techniques, see “Disk Media Management” in Chapter 6 of this manual.