Figure 3.1 Data Buffer Configuration (In The Case Of 8 Cache Segments) - Fujitsu MAU3147RC SERIES Technical Manual

Data Buffer Management
INIT
Write→
←Read

Figure 3.1 Data buffer configuration (in the case of 8 cache segments)

The basic functions and operations of the data buffer in a read operation and a
write operation are shown below.
(1) Read operation
Data read from the disk media are temporarily stored in the data buffer.
Then, they are transferred to the interface with the timing specified by the
IDD. The basic read operation procedure is as shown below.
1) When the IDD receives a command, it temporarily closes the connection
2) When the target data block has been located, the IDD reads the data form
3) When the IDD has read out to the data buffer the amount of data that the
4) If the data transfer rate of the INIT is high and the data buffer becomes
3-2
Valid Data
and locates the data block specified by the command on the medium.
the disk media to the data buffer. At this time, if a recoverable error is
detected, the IDD performs error recovery processing according to the
specification in the MODE SELECT parameter or corrects the data in the
data buffer.
IDD itself has specified, it performs reconnection processing with the
interface and begins transferring data to the INIT from the data buffer
while continuing to read subsequent data blocks out to the data buffer.
empty before completing the transfer of the number of data blocks
specified by the command, the IDD closes the interface at this point.
Thereafter, opening, data transfer, and closing operations (the operations
in 3) and 4) above) are repeated until all the data blocks specified in the
command have been transferred.
Segment
Segment 7
Segment 6
Segment 5
Segment 4
Segment 3
Segment 2
Segment 1
Segment 0
Write→
←Read
Disk Media
C141-C009