Read-Ahead Cache; Data Buffer Structure; Figure 6.7 Data Buffer Structure - Fujitsu MHW2080AT Product Manual

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) 2MB buffer (2,097,152 bytes)
For MPU work
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
2,097,152 bytes
For R/W command

Figure 6.7 Data buffer structure

C141-E250