JPH0378043A - Data update system for direct-read-after-write draw) type medium - Google Patents

Abstract

PURPOSE:To eliminate a waste of an area on the DRAW type medium by storing data in process of update processing in an updated data file which is rewritable and writing the updated data and file area control data on the additionally rewrite medium at he end of the update processing. CONSTITUTION:When there is a request to update data on the DRAW type medium 1 from an update request program 4, the data is outputted to an unused area of the updated data file 6 and an updated data control table 7 is corrected. When the processing of the update request program ends, the data of the file 6 are outputted to an unwritten area of the medium 1 and the start position of the table 7 is changed to the position of an output destination of the medium 1. After the data of the file 6 are outputted to the medium 1, the data of the table 7 are outputted to the unwritten area of the medium 1 as new area control data. Consequently, the waste of the area of the DRAW type medium can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for updating data on a write-once medium.Prior art: Conventionally, the following methods have been known for updating data contents on a write-once medium. was.

Allocate a new area on the write-once medium, create a file, input data one by one from the old file, output the data that does not need to be updated to the new file, and update the data that needs to be updated. In this case, the updated data is output to a new file (method 1).

Data that needs to be updated is read from a file on a write-once type medium, and after the update is made, that data block is additionally output to the unwritten area at the end of the file, and file area management data is also created each time. Method for loading the medium into the upper stage (method 2).

The data that needs to be updated is read from the file on the write-once medium, and after the update is made, the data block is additionally output to the unwritten area at the end of the file, and after all the data has been updated, the file area management data is A method of creating a new file and writing it to a write-once medium (method 3).

Problems to be Solved by the Invention However, in the conventional method 1 mentioned above, a new file is created even when one piece of data is updated, so there is a problem that the area of the write-once medium is wasted. there were.

In addition, in method 2 described above, one data block is written every time one data is updated, so when multiple data in one data block are updated, that data block must be added many times. This method has the same problem as method 1 in that writing occurs and the area of the write-once medium is wasted, although it is not as bad as in method 1 above. Furthermore, since new file area management data is created every time one piece of data is updated, there is another problem in that the area of the write-once medium is wasted.

Method 3 described above eliminates wasted file area management data, but if an error occurs during data update processing and the process is interrupted, a mismatch between the written data block and the file area management data may occur. , there is a problem in that the file will no longer be processed normally.

The present invention has been made in view of the above-mentioned conventional situation,
Therefore, an object of the present invention is to provide a new data update method for a write-once medium that makes it possible to solve the above-mentioned problems inherent in the conventional technology.

Means for Solving the Problems In order to achieve the above object, the data update method of the write-once medium according to the present invention is such that no data can be written to an area where data has been written again, and data is not written to an unwritten area. In a write-once medium on which only additional writing can be performed, a file on the write-once medium, file area management data on the write-once medium that manages a file area on the write-once medium, and the write-once medium An update request program that requests an update of the contents of the above file, and an update request program that requests updating of the contents of the above file.
a data access processing means for accessing data to a file on the write-once medium in response to a data access request from a program; an update data file on a rewritable medium for temporarily storing updated data; and an update process. and an update data management table for managing an intermediate file area, and the data access processing means secures the update data file and updates the file area upon receiving a file open request from the update request program. Input management data to set initial data in the update data management table, and when receiving a data input request from the update request program, refer to the update data management table to see if the requested data has been updated yet. If the requested data is in a block of data that has not yet been updated, the data is input from the file on the write-once medium, and if the requested data is in a block of data that has already been updated, the requested data is input from the updated data file. and when receiving a data update request from the update request program, outputs the update data to the update data file and stores area information of the updated data block in the update data management table;
When a file close request is received from the update request program, data is read from the update data file based on the information in the update management data table, and additionally outputted to an unwritten area of the file on the write-once medium; The present invention is characterized in that the area before the update is deleted from the data block whose data has been updated, and the area in which new additional writing has been performed after the update is added to create new file area management data.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

Referring to FIG. 1, one embodiment of the present invention updates and updates a write-once medium 1, file area management data 2 on the medium, file 3, and data in file 3 on the write-once medium 1. Update request program 4 and write-once medium 1
a data access processing means 5 that processes access to the above file 3; an update data file 6 on a rewritable medium that temporarily stores updated data during data update processing of the file 3 on the write-once medium 1; It is composed of an update data management table 7 for managing file area data during update processing.

FIG. 2 shows an example of the areas of file area management data 2 and file 3 on a write-once medium. In this example,
The file 3 consists of three areas Fl, F2 and F3, and the file area management data 2 manages the starting position and size of each area. Further, the file area F1 has three data blocks Bl, B2.
B3, and the file area F2 stores three data blocks B4. B5. Store B6 and file area F3
is two data blocks B7. B8 is stored.

FIG. 3 shows the update data management table 7 during data update, the area of the file 3 on the write-once medium 1, and the contents of the update data file 6. It consists of the number of entries for the number of file areas currently being managed (six in this example) and each file area entry. In this example, the file area Fl in the write-once medium 1 is
The contents of block B3 are updated and stored in the update data file 6, and data is added to block B5 in the file area F2, divided into two blocks, blocks B5-1 and B5-2, and stored in the update data file 6. This shows a state in which all the data in block B8 of file area F3 has been deleted. Note that the original location of the updated data block in the file area in the write-once medium 1 is indicated by a dotted line.

FIG. 4 is a diagram explaining the processing steps of the data access processing means 5.

Referring to FIG. 4, first, when a file open request is issued from the update request program 4, step 50
1, the update data file 6 is secured, and the file area management data 2 is input to initialize the update data management table 7. When a data input request is issued from the update request program 4, in step 502, a corresponding file area entry is searched from the update data management table 7 based on the relative position of the requested data in the file. As a relative position within the file, if data is accessed sequentially, this is the block that stores the next data, and if data is accessed randomly, it can be determined from the block number specified in the data request. Next, in step 502, it is determined whether the file area containing the requested data is in the write-once medium 1 or in the update data file 6 by referring to the file area identifier of the entry. If the area is on write-once medium 1, step 50
Step 4 inputs the target block from the write-once medium 1 into the buffer, and if the area is in the update data file 6, the target block is input from the update data file 6 into the buffer in step 505.

It goes without saying that in the processing of steps 504 and 505, if the block containing the target data has already been input to the buffer, the input processing is not performed, and in step 506 the requested data is transferred from the buffer to the update request program. Pass it and end the data input request processing. When there is a data update (update, addition, deletion) request from the update request program 4, first, in step 507, the data on the buffer is updated. In step 508, it is determined whether the block on the buffer is input from the write-once medium 1 or from the update data file 6. If the input is from a write-once medium, step 50
9 updates the block on that buffer data file 6
The update data management table 7 is corrected by newly outputting the update data to an unused area of the update data management table 7. If the input is from the update data file 6, the block on the buffer will be written back to the original update data file 6. If the number of blocks is increased due to data addition, the increased block will be written back to the original update data file 6. The data is written in the used area, and further, it is determined in step 511 whether there is any change in the file area information, and if a change is necessary, the update data management table 7 is changed in step 512. When all the data update processing of the update request program has been completed and a file close request has been issued, the update data management table 7 is referred to in step 513, and if the block is on the update data file 6, it is added to the write-once type. The light is output to an unwritten area of the medium 1, and the start position of the update data management table 7 is changed to the position of the output light of the write-once medium 1. After all blocks on the update data file 6 have been output to the write-once medium 1, the update data management table 7
Data other than the file area identifier is output to the unwritten area of the write-once medium 1 and used as new file area management data 2. Finally, the update data file 6 is released and the closing process is completed.

As described in detail, according to the present invention, when updating data on a write-once medium, the data in the middle of the update process is stored in an update data file on a rewritable medium, and when the update process is completed, the data is Since the updated data and file area management data are written in the write-once medium, the effect is that the area of the write-once medium is not wasted.

Further, according to the present invention, since nothing is written to the write-once medium during the update process, even if an abnormality occurs during the update process and the update process is interrupted, the data on the write-once medium remains as it was before the update, and there is also the effect that no mismatch occurs between the file area management data and the actual data block.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure shows the relationship between file area management data and file areas, Figure 3 shows the relationship between the update data management table and file areas, and Figure 4 shows data access processing.
FIG. 3 is a step diagram of the means.

Claims (1)

[Scope of Claim] A write-once medium in which data cannot be written to an area once data has been written therein, and data can only be additionally written to an unwritten area, comprising: a file on the write-once medium; File area management data on a write-once medium that manages a file area on the write-once medium, an update request program that requests updating of the contents of a file on the write-once medium, and data access from the update request program. A data access processing means for accessing data to a file on the write-once medium in response to a request, an update data file on a rewritable medium for temporarily storing updated data, and a file area in the middle of update processing. and an update data management table for managing the update data, and when the data access processing means receives a file open request from the update request program, the data access processing means secures the update data file and inputs the file area management data to manage the update data. When initial data is set in the table and a data input request is received from the update request program, the update data management table is referred to and if the requested data is within a data block that has not been updated yet. Input data from the file on the write-once medium, and if the requested data is in a block of data that has already been updated, input the requested data from the update data file, and issue a data update request from the update request program. If so, output the updated data to the updated data file and store area information of the updated data block in the updated data management table,
When receiving a file close request from the update request program, read data from the update data file based on information in the update management data table and additionally output the data to an unwritten area of the file on the write-once medium;
Furthermore, the data of the write-once medium is characterized in that the area before the update is deleted from the data block whose data has been updated, and the area where new additional writing has been performed after the update is added to create new file area management data. Update method.