JPS63271769A - Data correction system for non rewritable medium - Google Patents

Abstract

PURPOSE:To use the minimum quantity of resources regardless of the sequential processing or the random processing applying a record positioning function, by recording temporarily a corrected block of a nonwritable medium to a rewritable medium and finally updating the extent information on a file label added to an unwritten area of the nonwritable medium. CONSTITUTION:An input/output control means 4 replaces an original data record of a block supplied in an input request state with a corrected data record to deliver it to an unwritten part in an index file 3 and at the same time registers a data block position in the file 3 as a record using the block number as the key value. When the means 4 receives a closing request of a data file 1, the means 4 supplies all data blocks in the file 3 in the order of keys to copy them into the unwritten parts at the rear side of the file 1 and updates the extent information stored in a file label 5. In such a constitution, the minimum quantity of resources is consumed regardless of the forward processing or the random processing applying a record positioning function.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to file access involving data modification on a non-rewritable medium in which data cannot be written to the same part again after data has been written. .

[Conventional technology]

Traditionally, data modification was done by making it impossible to modify file contents on non-rewritable media, or by creating a new file and copying the data to it in a format that contains the modified data. .

(Problem to be solved by the invention) As mentioned above, when data cannot be modified, only data that has not been modified at all can be written on a non-rewritable medium, which requires extreme care when using it, and the scope of use is narrow. It was something.

In addition, with the method of creating a new file and copying it there, there is no problem if the file size is small if it is processed sequentially, but if the file size is large, even if a part of the file is modified, the same size Since it requires a file, it is wasteful, and if the file positioning is done randomly using a function, it is impossible to modify the data.

[Means for solving problems]

Data modification method on non-rewritable media of the present invention Once data is written, data cannot be written to the same part again File attributes of data files on non-rewritable media and positions within the media Attached are a file label with extent information, an input/output request program that requests input/output to the data file, and a rewrite program for temporarily managing modified blocks of the data file until the data file is closed. receiving a request from the input/output requesting program when the input/output requesting program reads data records in the data file sequentially or randomly using a record positioning function; Search the index file using the block number in the data file as a key value, and if the block you want to input does not exist, input the corresponding block on the non-rewritable medium, and if the block you want to input exists in the index file. inputs the corresponding block on the indexed file, passes the data record in the input block to the input/output request program, and if the input/output request program requests modification of the input data record, the input/output request program After receiving a request from the output request program and replacing the original data record and modified data record on the block input at the time of the input/output request, the index file at the time of the input request is registered in order to register the updated block on the index file. If the block is an input block from the index file, the data block on the index file is updated, and if the block was input from the data file without being input from the index file at the time of the input request, the data is added to the rear unwritten portion of the index file. By outputting a block and registering it on the index file as a record with a block position using the block number as a key value, it is possible to input new data from the modified block in response to subsequent data record input requests, and when the file is closed. , input the index file in key order, copy all data blocks in the index file to the rear unwritten part in the data file, and update the extent information in the file label information of the data file to prevent rewriting. There is input/output control means for bringing the media up to date.

(Operation) By temporarily recording a modification block for a non-rewritable medium on a rewritable medium, and finally adding it to the unwritten area on the non-rewritable medium and updating the extent information on the file label, Even in sequential processing, the positioning of records requires minimal resources even when random processing is performed using functions.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating an embodiment of the data modification method on a non-rewritable medium of the present invention.

This embodiment uses a file label 5 that has the file attribute of a data file 1 on a non-rewritable medium that cannot write data to the same part again after data has been written, and an input to the data file 1. An input/output request program 2 that requests output, an index file 3 on a rewritable medium for temporarily managing modified blocks of data file 1 until the data file is closed, and data file 1 and index file 3. The input/output control means 4 controls input/output to and from the input/output controller.

Next, the operation of this embodiment will be explained. First, when the input/output request program 2 creates the data file 1, it creates the data file 1 and the file label 5 as before.

Next, data record input from data file 1 and data record modification will be explained. The input/output request program 2 requests the input/output control means 4 to input data records in the data file 1 sequentially or randomly. The input/output control means 4 searches for a record using the block number of the block containing the record to be input as a key value from the index file 3, and if the record does not exist, inputs the data block from the normal block position of the data file 1, and checks if the record exists. If so, the data block in the index file 3 is input from the block position in the record having that key value, and the requested data record from within the input block is passed to the input/output request program 2. Then, the input/output request program 2 refers to the input data record, and if necessary, modifies the data record and passes it to the input/output control means 4, requesting that it be replaced with the original data record. The input/output control means 4 replaces the original data record on the block input at the time of the input request with the corrected data record, and replaces the unwritten portion in the index file 3 or the index file 3.
When outputting to an unwritten portion, the data block position in the index file 3 is registered as a record with the block number as a key value.

Next, file close processing will be explained.

The input/output control means 4 receives a request to close the data file 1 from the input/output request program 2, inputs all data blocks in the index file 3 in key order, and closes the data file 1.
Copy it to the rear unwritten part of
Update internal extent information.

Figure 2 shows blocks X, Y and Z of data file 1.
This shows the state in which the file has been corrected and registered in index file 3.

FIG. 3 shows the state of data file 1 and file label 5 after data file 1 is closed from the state of data file 1 shown in FIG.

In data file 1, modified blocks X, Y, and Z are additionally output to unused areas, and blocks X, Y, and 2 before modification cannot be rewritten, so they remain as they are. In the file label 5, the positions of the modified blocks X, Y, and Z are reflected in the extent information, so that even if the data file 1 is referred to based on the extent information, the modified blocks can be input correctly.

4 to 6 are flowcharts showing each process of the input/output control means 4. FIG.

(1) FIG. 4 shows input processing of data records from data file 1. First, when an input request is received from the input/output request program 2, the index file 3 is searched (step 41), it is determined whether or not a block containing the target data record exists (step 42), and if it exists, the index file 3 is searched (step 41). If the data block does not exist, the data block in data file 1 is input (step 44), and the desired data record is extracted (step 45).

(2) FIG. 5 shows a modification process for modifying data records. First, the modified data record is received from the input/output request program 2, and the unmodified data record in the data block input at the time of the input request is replaced with the modified data record (step 51). It is determined whether or not a data block has been input (step 52), and if it has been input from index file 3, the corresponding block on index file 3 has been replaced (step 53), and it has been input from data file 1 instead of from index file 3. In the case of a block, the data block is output to the rear unwritten portion of the index file 3 (step 54), and the data block position in the index file 3 is registered in the index file 3 as a record with the block number as the key value (step 54). 55).

(3) FIG. 6 shows file closing processing.

First, a step 61) of indexing a part of the key in the index file 3 and extracting the position of one modified block, a step 62) of inputting one block in the index file 3 from the retrieved modified block position, Step 63) to update the extent information, step 64) to determine whether a modified block still exists on the index file 3, step 65).
If it exists, the process returns to step 61 and the following process is repeated.

In this embodiment, data file 1 and index file 3 are input/output for each input and modification request, but normally input/output is performed for each block and buffering is performed using multiple buffers to improve performance. It turns out.

(Effects of the Invention) As explained above, the present invention temporarily records a modified block on a non-rewritable medium, and finally adds it to an unwritten area on the non-rewritable medium. By updating the extent information on the file label, record positioning can be controlled as if it were rewritable with a minimum amount of resources, even in sequential processing or random processing using functions, thereby eliminating the drawbacks of non-rewritable media. This has the effect of being able to expand the scope of its use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the data modification method on a non-rewritable medium of the present invention, FIG. 2 is a state diagram after multiple blocks are modified, and FIG. 3 is a state diagram after file closing. 4 to 6 are flowcharts of each process of the input/output control means 4. 1----- Data files on non-rewritable media;
2...Input/output request program. 3... Index file on rewritable medium, 4
--------Input/output control means, 5---File label, 41.42, 43, 44.45---Each step of input processing, 51.52, 53, 54.55・・・・・・
・Each step of correction process, 61.62, 63, 64.6
5...--Each step of the closing process. Figure 5 of Ward 1

Claims (1)

[Claims] File attributes of data files on non-rewritable media and extent information, which is positioning information within the media, are stored on a non-rewritable medium where data cannot be written to the same area again after data has been written. an input/output request program that requests input/output to the data file; and an index file on a rewritable medium for temporarily managing modified blocks of the data file until the data file is closed. , when the input/output requesting program reads data records in the data file sequentially or randomly using the record positioning function, it receives a request from the input/output requesting program and sets the block number in the data file as a key value. If the block you want to input does not exist, input the corresponding block on the non-rewritable medium, and if the block you want to input exists in the index file, search the index file. When the input/output request program receives a request from the input/output request program and passes the data record in the input block to the input/output request program, and the input/output request program requests modification of the input data record, the input/output request program After replacing the original data record and modified data record on the block input at the time of the request, in order to register the updated block on the index file, if the input block is from the index file at the time of the input request, the index file Update the upper data block, and if the block was input from the data file instead of from the index file at the time of input request, output the data block to the rear unwritten part of the index file, and set the block number as the key value. By registering the record in the index file as a record with the block position set as above, it is possible to input a new data from the corrected block in response to a subsequent data record input request, and when the file is closed, the index file is input in key order, Input/output control that copies all data blocks in the index file to a rear unwritten portion in the data file and updates extent information in file label information of the data file to bring the non-rewritable medium to the latest state. A method for modifying data on non-rewritable media having means.