Read-Ahead Cache; Data Buffer Configuration - Fujitsu MPE3XXXAE Product Manual

6.5

Read-Ahead Cache

After a read command which reads the data from the disk medium is completed, the read-
ahead cache function reads the subsequent data blocks automatically and stores the data in the
data buffer.
When the next command requests to read the read-ahead data, the data can be transferred from
the data buffer without accessing the disk medium. The host can access the data at higher
speed.
6.5.1

Data buffer configuration

The device has a 512-KB data buffer. The buffer is used by divided into two and other
commands parts; for MPU work, for read cache of read commands and other commands (see
Figure 6.9).
for MPU work
63 KB
(64,512 bytes)
The read-ahead operation is performed at execution of the READ SECTOR(S), READ
MULTIPLE, or READ DMA command, and read-ahead data are stored in the buffer for read
cache.
512 KB (524,288 bytes)
for READ command
305 KB
(312,832 bytes)
Figure 6.9

Data buffer configuration

C141-E093-01EN
for WRITE command
132 KB
(135,168 bytes)
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