Fujitsu MHN2100AT Manual Do Utilizador
Operations
6-12
C141-E120-02EN
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
thus access data at higher speed.
transferred from the data buffer without accessing the disk medium. The host can
thus access data at higher speed.
6.4.1 Data buffer configuration
The drive has a 2 MB data buffer. The buffer is used by divided into three parts;
for read/write commands, and for MPU work (see Figure 6.9).
for read/write commands, and for MPU work (see Figure 6.9).
for MPU works
for read/write commands
2048 KB
80 KB
1968 KB
Figure 6.7 Data buffer configuration
The read-ahead operation is performed at execution of the READ SECTOR(S),
READ MULTIPLE, or READ DMA command, and read-ahead data is stored in
the buffer for read/write commands.
READ MULTIPLE, or READ DMA command, and read-ahead data is stored in
the buffer for read/write commands.
6.4.2 Caching operation
Caching operation is performed only at issuance of the following commands. The
device transfers data from the data buffer to the host system at issuance of
following command if following data exist in the data buffer.
device transfers data from the data buffer to the host system at issuance of
following command if following data exist in the data buffer.
•
All sectors to be processed by the command
•
A part of data including load sector to be processed by the command
When a part of data to be processed exist in the data buffer, remaining data are
read from the medium and are transferred to the host system.
read from the medium and are transferred to the host system.
(1) Commands that are object of caching operation
Follow commands are object of caching operation.
•
READ SECTOR (S)
•
READ MULTIPLE
•
READ DMA
When caching operation is disabled by the SET FEATURES command, no
caching operation is performed.
caching operation is performed.
(2) Data that are object of caching operation
Follow data are object of caching operation.