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3.1 Data Space
C141-E237 3-3
(1) User space
The user space is a storage area for user data. The data format on the user space (the length of data
block and the number of data blocks) can be specified with the MODE SELECT or MODE SELECT
EXTENDED command.
The user can also specify the number of logical data blocks to be placed in the user space with the
MODE SELECT or MODE SELECT EXTENDED command. When the number of logical data
blocks is specified, as many cylinders as required to place the specified data blocks are allocated in
the user space.
A number starting with 0 is assigned to each cylinder required in the user space in ascending order.
If the number of cylinders do not reach the maximum, the rest of the cylinders will not be used.
Always one cylinder is located at the end of each zone in the user space as an alternate cylinder.
Alternate cylinders will be used for alternate blocks. See Subsections 3.1.2 and 3.3.2 for details.
(2) Internal test space
The internal test space is an area for diagnostic purposes only and its data block length is always
512Byte. The internal test space consists of 8 cylinders and outer-most cylinder is always assigned
(cylinder −147 to −154). The user cannot change the number of cylinders in the internal test space or
their positions.
(3) System space
The system space is an area for exclusive use of the HDDs themselves and the following information
are recorded.
• Defect list (P list and G list)
• MODE SELECT parameter (saved value)
• Statistical information (log data)
• Controller control information
The above information is duplicated in several different locations for safety.
Note:
The system space is also called SA space.