Fujitsu MHW2040AC User Manual download pdf (Page 256)

Operations

6.4.3.2 Sequential hit

When the read command that is targeted at a sequential address is received after

execution of the read commands is completed, the read command transmits the

Read requested data to the host system continuing read-ahead without newly

allocating the buffer for read.

1) When the sequential read command is received, HAP is set in the sequential

address of the last read command, and DAP is set at a present read position as

it is.

Read-ahead data

Cache valid data Free space

Read requested data

DAP (disk address pointer)

HAP (host address pointer)

2) During reading of read requested data, the request data that has already been

read is sent to the host system.

Cache valid data Free space

Read requested data

DAP (disk address pointer)

HAP (host address pointer)

3) When reading of read requested data is completed and transfer of the read

requested data to the host system is completed, the read-ahead operation

continues until a certain amount of data is stored.

Read-ahead

data

Cache valid data

Free

space

Read requested data

DAP (disk address pointer)

HAP (host address pointer)

Read-ahead

data

4) The following cache valid data is for the read command that is executed next:

Cache valid data

START LBALAST LBA

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Fujitsu MHW2040AC User Manual Page 256