Computer Drive User Manual

C141-E078-02EN 3 - 9
3.1.5 Format capacity
The size of the usable area for storing user data on the IDD (format capacity) varies according to
the logical data block or the size of the spare sector area. Table 3.3 lists examples of the format
capacity when the typical logical data block length and the default spare area are used. The
following is the general formula to calculate the format capacity.
[Number of sectors of each zone] = [number of sectors per track × number of tracks (heads) –
number of alternate spare sectors per cylinder] × [number of cylinders in the zone]
[Formatted capacity] = [total of sectors of all zones] – [number of sectors per track in last zone ×
number of tracks (heads) × number of alternate cylinders] ÷ [number of physical sectors in logical
block] × [logical data block length]
The following formula must be used when the number of logical data blocks are specified with
the parameter in the MODE SELECT or MODE SELECT EXTENDED command.
[Format capacity] = [logical data block length] × [number of logical data blocks]
The logical data block length, the maximum logical block address, and the number of the logical
data blocks can be read out by a READ CAPACITY, MODE SENSE, or MODE SENSE
EXTENDED command after initializing the disk medium.
Table 3.3 Format capacity
Model Data heads Data block length User blocks Format capacity (GB)
MAF3364FC 19 512 71,161,520 36.43
MAG3182FC 10 512 35,694,860 18.27
MAG3091FC 5 512 17,827,698 9.12