Electrical computers and digital processing systems: memory – Storage accessing and control – Memory configuring
Reexamination Certificate
1998-09-17
2001-05-01
Kim, Matthew (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Memory configuring
C711S171000
Reexamination Certificate
active
06226727
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a computer system having a recording/reproducing device which uses a DVD-RAM or the like as a recording medium. More particularly, the invention relates to a computer system that can record data in the most desirable manner even if a logical block and a record block differ in size.
This application is based on Japanese Patent Application No. 09-253713 filed on Sep. 18, 1997, the content of which is cited herein by reference.
Generally, a recording/reproducing device (recording media device) can be connected to or incorporated in a personal computer or a portable computer, so that it may be used as an external memory.
The file system (i.e., the computer), which manages the writing of data into and the reading of data from an external memory, has two types of data blocks. The first type is a logical block, which is a logical unit of data. The second type is a record block, which is a unit of data to be written into or read from the recording medium provided in the external memory.
In the actual data-writing process, not only the data managed in the form of the logical block, but also error correction codes and the like are recorded on the recording medium. This means that the record block has the same size as a unit of data to be subjected error correction. The record block must be identified in the file system so that the file system may efficiently access to the recording media device. To this end, the recording media device is designed to access the file system in the logical block, which corresponds to the record block. The file system manages data such as files, in units of logical blocks, efficiently exchanging data with the recording medium.
As indicated above, the logical block which the file system manages and the record block which is a unit of data to be written into or read from the recording medium by the recording media device have the same size in most cases. In some file systems, the size of the logical block may be defined to the multiple size of the record block. This is because the number of logical blocks which the file system can manage is limited, and the number of logical blocks must be reduced.
Manufacture of recording media of a large storage capacity has been started, thanks to the recent developed technique of increasing recording density. Streams of image data and streams of sound data are recorded on a recording medium which has a large storage capacity. It is better to perform error correction on such a recording medium which has a large storage capacity in units of larger data blocks than in units of relatively small data blocks as conventionally employed. The reason is that the overhead is smaller when the data is corrected in units of larger blocks, ultimately enhancing the storage efficiency. Therefore, the size of the record block may be larger on a recording medium of large storage capacity.
In some cases, however, the size of the logical block cannot be larger corresponding to the size of the record block. If the logical blocks are made as large as the record blocks, they may no longer be compatible with the logical blocks on the conventional recording medium, or may no longer conform to the applied standards. For example, the EEC (Error Correcting Code) blocks (i.e., record blocks) on a DVD (Digital Versatile Disc) have a size of 32 KB, whereas the logical blocks on the DVD have a size of 2 KB as is designated on the basis of the standards. In other words, an error correction code (ECC) is added to every 16 logical blocks. When the logical blocks differ in size from the record blocks as in this case, the speed of accessing the recording medium and reliability may inevitably decrease.
BRIEF SUMMARY OF THE INVENTION
The first object of the present invention is to provide a computer system which can improve access speed and reliability in recording and reproducing even if a logical block have a size different from the size of a record block.
The second object of the invention is to provide a data management method for use in data processing apparatus.
To achieve the first object, there is provided a computer system in which logical blocks and record blocks are set in different size. The computer system comprises: allocation means for allocating the logical blocks and the record blocks in multiple units of a common block for data to be written in writing the data on a recording medium, the common block having a size of the least common multiple of the size of the logical block and the size of the record block, and the front of the allocated logical blocks coinciding with the front of the allocated record blocks; managing means for instructing that the data be written in multiple units of a common block allocated by the allocation means; and writing means for writing the data on the recording medium in accordance with instructions given by the managing means.
To achieve the second object, there is provided a data management method applied to a data processing apparatus in which logical blocks and record blocks are set in different size. The method comprises a step of allocating the logical blocks and the record blocks in multiple units of a common block for data to be written in writing the data, the common block having a size of the least common multiple of the size of the logical block and the size of the record block, and the front of the allocated logical blocks coinciding with the front of the allocated record blocks.
In this computer system described above, logical blocks and record blocks are allocated in multiple units of a common block for data to be written in writing data on a recording medium and the front of the allocated logical blocks coincides with the front of the allocated record blocks. Hence, a plurality of extents can not exist in the same record block. This prevents errors from occurring in the data not being accessed, even if troubles occur in reading or writing any other data.
Since the managing means instructs that the data be written in multiple units of a common block allocated by the allocation means, it suffices to read data in record blocks corresponding to the units of common blocks into a memory. This may improve the access speed.
In the computer system, the allocation means may be designed to divide the data into parts having a size equal to or smaller than a multiple size of the common block when the data has a size larger than that of the common blocks.
Alternatively, the allocation means may be designed to change the allocation when the recording medium has come to have a defect, thereby to replace the allocated common block having a defect with another common block in which no data has been recorded.
As described above, data is divided into parts having a size equal to or smaller than a multiple size of common block in the computer system of this invention, and the system can therefore process data at an increased speed. Even if the recording medium has come to have a defect, the common block having the defect can be replaced by another common block in which no data has been recorded. This also may improve the data-processing speed.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 5485321 (1996-01-01), Leonhardt et al.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Kim Matthew
Williams, II Jan S.
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