Electrical computers and digital processing systems: memory – Storage accessing and control
Reexamination Certificate
2000-11-16
2003-03-11
Yoo, Do Hyun (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
C711S113000, C711S134000, C711S170000
Reexamination Certificate
active
06532513
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information recording and reproduction apparatus for improving the speed of data recording and reproduction by temporarily storing data to be transferred between a host computer and a recording medium in a cache memory.
2. Description of the Related Art
An information recording and reproduction apparatus used as an external memory apparatus of a host computer, such as an optical disk apparatus, reads data from and writes data into a recording medium at a lower speed than a speed of data transfer between the information recording and reproduction apparatus and the host computer. In order to improve the speed of recording and reproduction, it has recently become common to provide a cache memory for temporarily storing data in the information recording and reproduction apparatus so that data is transferred through the cache memory.
The information recording and reproduction apparatus having such a cache memory performs as follows.
When a data read operation is requested from the host computer, the information recording and reproduction apparatus reads the requested data from the recording medium and also reads data which is expected to be requested (a so-called “read-ahead” system).
When a data write operation is requested from the host computer, the information recording and reproduction apparatus notifies the host computer of the completion of the data write operation when the data to be written is stored in the cache memory and then writes the stored data into the recording medium (a so-called “write-back” system).
Such an information recording and reproduction apparatus generally uses a ring buffer system of using the cache memory in repetition. Accordingly, an effect of the cache memory is provided for reading data from or writing data into a single continuous area of the recording medium, but a sufficient effect of the cache memory cannot be provided when accesses to a plurality of discrete areas of the recording medium a re required.
In order to solve this problem, a system of dividing the cache memory into a plurality of ring buffers has been proposed. When a plurality of, for example, two, ring buffers are used, a sufficient effect of the cache memory can be provided to improve the processing speed even when accesses to more than one, in this case, two discrete areas of the recording medium are required.
However, this system of dividing the cache memory into a plurality of ring buffers has the following problem. When the number of the ring buffers is smaller than the number of the discrete areas of the recording medium to be accessed, all of the discrete areas cannot correspond to the ring buffers. As a result, the effect of the cache memory is reduced. When the number of the ring buffers is larger than the number of the discrete areas of the recording medium to be accessed, all the ring buffers are not used. As a result, the cache memory cannot be used efficiently. In other words, a sufficient effect of the cache memory cannot be provided depending on the number of the ring buffers, the size of each of the ring buffers, and the access pattern from the host computer (i.e., access to a single continuous area or access to a plurality of discrete areas).
SUMMARY OF THE INVENTION
According to an information recording and reproduction apparatus includes a data transfer controller for receiving data to be written transferred from a host computer; a cache data memory divided into a plurality of segments for temporarily storing the data to be written received by the data transfer controller; a segment connection information memory for storing segment connection information representing a logical connection state of the plurality of segments; a buffer memory controller for managing the data to be written temporarily stored in the cache data memory; and a recording and reproduction controller for writing the data to be written temporarily stored in the cache data memory into a recording medium. The buffer memory controller updates the segment connection information so as to change the logical connection state of the plurality of segments.
In one embodiment of the invention, the buffer memory controller changes a used segment among the plurality of segments into an unused segment so as to obtain a sufficient number of unused segments in order to process the data to be written, and updates the segment connection information so as to logically connect the unused segments.
In one embodiment of the invention, the buffer memory controller updates the segment connection information so as to logically connect the plurality of segments storing the data to be written, where the data is from sequential logical block addresses.
In one embodiment of the invention, the recording and reproduction controller sequentially writes the data to be written which is stored in the logically connected plurality of segments and is from sequential logical block addresses into the recording medium.
In one embodiment of the invention, the segment connection information memory stores the segment connection information as a unidirectional list.
In one embodiment of the invention, the segment connection information memory stores the segment connection information as a bidirectional list.
In one embodiment of the invention, the information recording and reproduction further includes a cache management information memory for storing management information on the data to be written temporarily stored in the cache data memory on a segment-by-segment basis of the plurality of segments.
In one embodiment of the invention, the management information includes an effective data flag which is set when effective data is stored in a segment of the plurality of segments, and a dirty flag which is set when unwritten data which has not been written into the recording medium is stored in the segment.
In one embodiment of the invention, at least two of the cache data memory, the segment connection information memory and the cache management information memory are structured as one memory.
According to another aspect of the invention, an information recording and reproduction apparatus includes a data transfer controller for receiving a data read request transferred from a host computer; a recording and reproduction controller for reading data to be read from the recording medium as requested by the host computer; a cache data memory divided into a plurality of segments for temporarily storing the data to be read which has been read by the recording and reproduction controller: a segment connection information memory for storing segment connection information representing a logical connection state of the plurality of segments; and a buffer memory controller for managing the data to be read temporarily stored in the cache data memory. The data transfer controller transfers the data to be read temporarily stored in the cache data memory to the host computer. The buffer memory controller updates the segment connection information so as to change the logical connection state of the plurality of segments.
In one embodiment of the invention, the buffer memory controller changes a used segment among the plurality of segments into an unused segment so as to obtain a sufficient number of unused segments to process the data to be read, and updates the segment connection information so as to logically connect the unused segments.
In one embodiment of the invention, the segment connection information memory stores the segment connection information as a unidirectional list.
In one embodiment of the invention, the segment connection information memory stores the segment connection information as a bidirectional list.
In one embodiment of the invention, the information recording and reproduction apparatus further includes a cache management information memory for storing management information on the data to be read temporarily stored in the cache data memory on a segment-by-segment basis of the plurality of segments.
In one embodiment of the invention,
Takauchi Kenji
Yabuno Hiroyuki
Yamamoto Yoshikazu
Matsushita Electric - Industrial Co., Ltd.
Moazzami Nasser
Snell & Wilmer L.L.P.
Yoo Do Hyun
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