FUJITSU MPG3XXXAH-E - Manual (Page 193)

C141-E116-01EN 6 - 16
(3) Sequential read
When the disk drive receives the read command that targets the sequential address to the previous
read command, the disk drive tries to fill the buffer space with the read ahead data.
a. Sequential command just after non-sequential command
1) At receiving the sequential read command, the disk drive sets the DAP and HAP to the
sequential address of the last read command and reads the requested data.
Empty data Mis-hit data
2) The disk drive transfers the requested data that is already read to the host system with
reading the requested data.
Requested data
DAP
HAP
Mis-hit data Empty data
3) After completion of the reading and transferring the requested data to the host system, the
disk drive performs the read-ahead operation continuously till a certain amount of data is
stored.
Mis-hit data Requested data
DAP
HAP
Empty
data
Read-
ahead
data
DAP
HAP