Read-ahead Cache, Data buffer structure | Fujitsu MHV2080AS specification

Operations

6.4 Read-ahead Cache

Read-ahead Cache is the function for automatically reading data blocks upon completion of the read command in order to read data from disk media and save data block on a data buffer.

If a subsequent command requests reading of the read-ahead data, data on the data buffer can be transferred without accessing the disk media. As the result, faster data access becomes possible for the host.

6.4.1 DATA buffer structure

This device contains a data buffer. This buffer is divided into two areas: one area is used for MPU work, and the other is used as a read cache for another command. (See Figure 6.7)

a) 8MB buffer (8,388,608 bytes)

8,388,608 bytes

For MPU work

For R/W command

557,056

7,831,552

bytes

Figure 6.7 Data buffer structure

The read-ahead operation is done by the following commands.

•

READ SECTOR(S) (EXT)

READ MULTIPLE (EXT) READ DMA (EXT) READ SECTOR(S) EXT READ DMA EXT READ MULTIPLE EXT

6-12

C141-E221

MHV2060AS, MHV2080AS, MHV2040AS specifications

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Fujitsu MHV2080AS, MHV2060AS Read-ahead Cache, Data buffer structure, 8MB buffer 8,388,608 bytes

Models: MHV2060AS MHV2080AS MHV2040AS