Fujitsu MHN2150AT Manual/User Guide - Page 218

Requested data, Mis-hit data, Empty area, HAP Completion of transferring requested data

Page 218 highlights

Operations 2) The disk drive transfers the requested data that is already read to the host system with reading the requested data. HAP Requested data Mis-hit data Empty area DAP 3) After completion of the reading and transferring the requested data to the host system, the disk drive performs the read-ahead operation continuously. HAP (Completion of transferring requested data) Requested data Read-ahead data Empty area DAP 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. HAP Read-ahead data DAP Last LBA Start LBA 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. 6-16 C141-E120-02EN

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Operations
6-16
C141-E120-02EN
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 area
3)
After completion of the reading and transferring the requested data to the host
system, the disk drive performs the read-ahead operation continuously.
Requested data
DAP
HAP (Completion of transferring requested data)
Empty area
Read-ahead data
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.