FUJITSU MPA3043AT User Manual
Page 168
C141-E034-02EN
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4)
The disk drive performs the read-ahead operation for all area of segment with overwriting
the requested data. Finally, the cache data in the buffer is as follows.
Start LBA
Last LBA
DAP
HAP
Read-ahead data
b. Sequential hit
When the previously executed read command is the sequential command and the last sector
address of the previous read command is sequential to the lead sector address of the received
read command, the disk drive transfers the hit data in the buffer to the host system.
The disk drive performs the read-ahead operation of the new continuous data to the empty area
that becomes vacant by data transfer at the same time as the disk drive starts transferring data
to the host system.
1)
In the case that the contents of buffer is as follows at receiving a read command;
Start LBA
Last LBA
DAP
HAP (Completion of transferring requested data)
Hit data
Read-ahead data
2)
The disk drive starts the read-ahead operation to the empty area that becomes vacant by
data transfer at the same time as the disk drive starts transferring hit data.
DAP
HAP
Hit data
New read-ahead data
Read-ahead data