Fujitsu MHT2030AT Manual/User Guide - Page 235
Using the read segment buffer
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6.4 Read-ahead Cache 6.4.3 Using the read segment buffer Methods of using the read segment buffer are explained for following situations. 6.4.3.1 Miss-hit In this situations, the top block of read requested data is not stored at all in the data buffer. As a result, all of the read requested data is read from disk media. 1) HAP (host address pointer) and DAP (disk address pointer) are defined in the head of the segment allocated from Buffer. (If pre-read is executed, HAP is set at the requested data reading position.) AP (host address pointer) Read segment DAP (disk address pointer) 2) During reading of read requested data, the request data that has already been read is sent to the host system. HAP Read requested data is stored until this point Read requested data Free space DAP 3) When reading of read requested data is completed and transfer of the read requested data to the host system is completed, reading of the disk continues until a certain amount of data is stored. HAP (stop) Read requested data Read-ahead data DAP C141-E192-02EN 6-15