Fujitsu MPF3XXXAT manual Usage of read segment, Hap, Dap

6.5.3Usage 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.

HAP

Segment only for read

DAP

2)Transfers the requested data that already read to the host system with reading the requested data from the disk media.

HAP

Stores the read-requested data upto this point

Read-requested data

Empty area

DAP

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.

HAP (stopped)

Read-requested data

Read Ahead Data

(stopped)

DAP

4)Following shows the cache enabled data for next read command.

Cache enabled data

Start LBA Last LBA

C141-E099-01EN 6 - 15