Fujitsu MHS2020AT, Product Manual

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6.4 Read-ahead Cache
C141-E171-03EN 6-19
6.4.3.4 Partial hit
In this situation, a part of read requested data including the top sector is stored in
the data buffer. A transfer of the read requested data starts from the address
where the data that is hit is stored until the top sector of the read requested data.
Remaining part of insufficient data is read then.
An example is a case where a partial hit occurs in cache data, as shown below.
LAST LBA
Cache valid data
START LBA
1) HAP is set at the address where partial hit data is stored. DAP is then set to
the address immediately after the partial hit data.
HAP
DAP
Partial hit data Insufficient data
2) At the same time as a transfer of the partial hit data starts, insufficient data is
read.
(stop)
HAP
Read requested data to be transferred
DAP
Partial hit data Insufficient data