Fujitsu MAN3184 User Manual
C141-E124-01EN
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1.8.2
Logical block addressing
The IDD uses logical data block addressing which is not dependent on the disk drive’s physical
structure as the method of data access on the disk medium. The IDD makes correspondence
between each physical sector and each logical data clock address during formatting. Access to the
data on the disk medium is performed in logical data block units and the INIT specifies the logical
data block address that is its object during access.
structure as the method of data access on the disk medium. The IDD makes correspondence
between each physical sector and each logical data clock address during formatting. Access to the
data on the disk medium is performed in logical data block units and the INIT specifies the logical
data block address that is its object during access.
In logical data block addressing, specifying of a data block address is a function which specifies 2
continuous binary numbers for each drive. Furthermore, the INIT can know the logical data block
address range in the user space where specification is possible using the READ CAPACITY
command.
continuous binary numbers for each drive. Furthermore, the INIT can know the logical data block
address range in the user space where specification is possible using the READ CAPACITY
command.
(1)
User space logical block addresses
The top data block in the user space is made logical data block address “0,” then continuous
logical data block addresses are allocated to each data block until the last data block in the user
space.
logical data block addresses are allocated to each data block until the last data block in the user
space.
The IDD makes cylinder 0, track 0 sector 0 the top logical data block, and allocates subsequent
logical data blocks in the order described below to addresses in ascending order.
logical data blocks in the order described below to addresses in ascending order.
1) Within the same track, logical data blocks are allocated to sector numbers in ascending order.
2) Within the same cylinder, excluding the final track, succeeding logical data blocks are
allocated to the sectors in each track according to 1) in the ascending order of track numbers.
3) Within the same cell, excluding the final track, succeeding logical data blocks are allocated to
the sectors in each track according to 1) in the ascending order of track numbers.
4) On the last track inside the same cell, succeeding logical data blocks are allocated to sectors
except for spare sectors according to 1).
5) After all the allocation in 1) to 4) is completed within the same cell, succeeding logical data
blocks are allocated to the next cell beginning with track 0, according to 1) to 3), and so on to
each cell number in ascending order until the last cylinder in each zone (refer to alternate
cilinder b-1 in Figure 1.5) in the user space, with the exception of alternate cylinders.
each cell number in ascending order until the last cylinder in each zone (refer to alternate
cilinder b-1 in Figure 1.5) in the user space, with the exception of alternate cylinders.
(2)
Alternate area
The alternate area in user space (spare sectors within each cylinder and alternate cylinders) are
excluded from the abovementioned logical data block addresses. Access to allocated sectors as
alternate blocks within the alternate area is performed automatically by the IDD’s defect
management (sector slip processing and alternate block processing), so it is not particularly
necessary for the user to access the alternate area. Also, data blocks in the alternate area cannot be
clearly specified and accessed directly.
excluded from the abovementioned logical data block addresses. Access to allocated sectors as
alternate blocks within the alternate area is performed automatically by the IDD’s defect
management (sector slip processing and alternate block processing), so it is not particularly
necessary for the user to access the alternate area. Also, data blocks in the alternate area cannot be
clearly specified and accessed directly.