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6-20 C141-E050-02EN
4) Finally, the cache data in the buffer is as follows.
Read-ahead data
c. Non-sequential command immediately after sequential command
When a sequential read command (first read) has been executed, the first
read operation should be stopped if a non-sequential read command has
been received and then, ten or more of the non-sequential read commands
have been received. (Refer to 6.5.3.1.)
The figure that describes the first read operation is the same as that
shown in the sub-section a.
6.5.3.3 Full hit (hit all)
All requested data are stored in the data buffer. The disk drive starts transferring
the requested data from the address of which the requested data is stored. After
completion of command, a previously existed cache data before the full hit
reading are still kept in the buffer, and the disk drive does not perform the read-
ahead operation.
1) In the case that the contents of the data buffer is as follows for example and
the previous command is a sequential read command, the disk drive sets the
HAP to the address of which the hit data is stored.
HAP (set to hit position for data transfer)
Last position at previous read command
Last position at previous read command
Cache dataFull hit dataCache data
2) The disk drive transfers the requested data but does not perform the read-
ahead operation.
(stopped)
HAP
Cache dataFull hit dataCache data
HAP
DAP
Last LBA
Start LBA