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C141-E090-01EN 6 - 15
6.5.3 Usage of read segment
This subsection explains the usage of the read segment buffer at following cases.
(1) Miss-hit (no hit)
A lead block of the read-requested data is not stored in the data buffer. The requested data is
read from the disk media.
1) Sets the host address pointer (HAP) and the disk address pointer (DAP) to the sequential
address to the last read segment.
Segment only for read
DAP
HAP
2) Transfers the requested data that already read to the host system with reading the requested
data from the disk media.
Read-requested data
Stores the read-requested
data upto this point
Empty area
DAP
HAP
3) After reading the requested data and transferring the requested data to the host system had
been completed, the disk drive continues to read till a certain amount of data is stored.
Read-requested data
Read Ahead Data
DAP
(stopped)
HAP
4) Following shows the cache enabled data for next read command.
Cache enabled data
Last LBAStart LBA
(stopped)