FUJITSU MPD3XXXAH User Manual

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C141-E072-01EN

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(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. If the disk drive receives a full hit command
while performing the read-ahead operation, the disk drive starts transfering the requested data
without stopping 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

Cache data

Full hit data

Cache data

2) The disk drive transfers the requested data but does not perform the read-ahead operation.

(stopped)

HAP

Cache data

Full hit data

Cache data

(4)

Partially hit

A part of requested data including a lead sector are stored in the data buffer. The disk drive
starts the data transfer from the address of the hit data corresponding to the lead sector of the
requested data, and reads remaining requested data from the disk media directly.

Following is an example of partially hit to the cache data.

Last LBA

Cache data

DAP

HAP

Start LBA