JPH0228848A - On-line data processing unit - Google Patents

Abstract

PURPOSE:To shorten time to be needed for recovery by causing the updating of an imperfect data base file to be ineffective with a table which is prepared based on the data to be read in the middle of the final volume of a journal file. CONSTITUTION:When the rerising of an on-line processing system is executed and recovery processing is started, it is judged whether a quick recovery file 6 is allocated to the on-line processing system or an access can be executed. When the file 6 can be utilized, the file 6 is read and the table for a journal block number 3000 and transaction numbers 100, 101 and 102 is held in an on-line processing process 2. When both files 4 and 5 can be utilized, recovery processing is executed from the file 4. Then, positioning is executed to a block 8, which has the block number 300, and the block is read into the on-line processing process 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a means for recovering an online data processing system after a system failure.

〔overview〕

The present invention provides a means for recovering after a system failure of an online data processing device that accesses database files and executes transactions, in which a list of incomplete database files is created based on data read from the middle of the final volume of a journal file. By disabling updates, the time required for recovery can be shortened.

[Conventional technology]

In the conventional method, a journal file is provided on either a magnetic disk device or a magnetic tape device, and all the information necessary for recovery is read from the beginning of the final volume, and the transactions that were being executed at the time of the system down are read. Create a list. Then, based on this list, before images of incomplete database file updates performed by transactions being executed at the time of system down are read from the journal file and written back to the database device for recovery.

[Problem that the invention seeks to solve]

Such conventional recovery methods have the disadvantage that recovery takes a considerable amount of time because all data must be read from the beginning of the final volume of the journal file.

The present invention aims to eliminate such drawbacks, and aims to provide an online data processing device in which the amount of data read from a journal file required for recovery is small.

[Means for solving problems]

The present invention provides online processing means for accessing database files and executing transactions, and storing information including update information related to incomplete database file updates due to transactions being executed at the time of a system down on a volume divided into blocks. In an online data processing device that is equipped with a journal file that is maintained in an area in chronological order and a recovery means that invalidates updated information based on a list of transactions that are being executed at the time of a system down, block a quick recovery file that retains the number assigned to the transaction and the number assigned to the executed transaction;
A table creation means for creating the list based on information read from the write position on the journal file positioned according to the contents of the quick recovery file to the write position at the time of system down. .

[Effect]

Reads information about the journal file and ongoing transactions at a certain point in time from the quick recovery file and maintains it in memory. Position the journal file to the final writing position based on the information from the quick recovery file. It reads the recovery necessary information on the journal file from the positioning position to the end of the journal file, that is, the system down, and creates a list of transactions that were being executed at the time of system down. In order to invalidate incomplete database file updates made by transactions that were being executed when the system went down, read the before-image of the database file update from the journal file based on this list and write it to the database file. return.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
7 is a block diagram of this embodiment, FIG. 2 is a block diagram of the journal file and quick recovery file of the embodiment of the present invention, and FIG. 3 is a diagram showing the recovery process selection procedure of this embodiment. It is.

As shown in FIGS. 1 and 2, this embodiment includes a terminal device 1 that inputs text to an online processing process 2 and displays messages from the online processing process 2, and a terminal device 1 that inputs text to an online processing process 2 and displays messages from the online processing process 2. An appropriate business program, that is, a transaction is selected based on the written text, the database file 3 is accessed, and the transaction start record 9, transaction end record 11, and before image 10 when updating the database file 3 are recorded in a disk journal. Writes to both file 4 and tape journal file 5, and writes the journal block number at the time of writing to quick recovery file 6 at certain regular intervals (in this example, the interval at which journal block 8 is written 1000 times). online processing process 2 that writes the transaction number of It includes a disk journal file 4 and a tape journal file 5 for holding, a tie recovery file 6 for holding journal block numbers written by the online processing process 2 and transaction numbers being executed, and a database file 3. That is, this embodiment is a journal file that stores information including update information related to incomplete updates of the database file 3 due to transactions being executed at the time of system downtime in an area on a volume divided into blocks in chronological order. Disk journal file 4 and tape serial file 5
a quick recovery file 6 that holds numbers assigned to blocks and numbers assigned to executed transactions for each predetermined number of blocks; online processing means that accesses the database file 3 and executes transactions; Table creation means for creating the list based on the information read from the writing position on the journal file positioned according to the contents of the quick recovery file 6 to the writing position at the time of system down; and and a recovery means for invalidating updated information based on the relevant list.

Next, as shown in FIG. 2, the operation of this embodiment when the system goes down immediately after the 3200th journal block 8 is written to the disk journal file 4 and tape journal file 5 will be described in FIGS. 1 to 3.
This will be explained with reference to the figures.

The online processing system is restarted and recovery processing is started (step SL). It is determined whether the quick recovery file 6 is assigned to the online processing system and can be accessed (step S2). If quick recovery file 6 is available, read quick recovery file 6 and get journal block number 3000 and transaction number 1.
A list of 00.101 and 102 is held in the online processing process 2 (step S3). Disk journal file 4 and tape journal file 5
are both assigned to the online processing system and can be accessed (step S).
4). If both the disk journal file 4 and the tape journal file 5 are available, recovery processing is performed starting from the disk journal file 4 (step S5).

That is, journal block 8 with journal block number 3000 (hereinafter journal block 3000
That's what it means. ) and read into the online processing process 2. Read the journal record in journal block 8 read based on the list of transaction numbers (hereinafter referred to as active list), and if it is transaction start record 9, add that transaction number to the active list and end the transaction. If it is record 11, that transaction number is deleted from the active list, and other records are skipped until the final journal block 3200. When this process is performed up to the final journal block 3200, the created active list will contain the transaction number 200 that was being executed at the time of the system down.
．． 201 and 202 are shown. Next, read from the end of disk journal file 4 backwards, read the before-images of transactions with transaction numbers 200.201 and 202 in the active list, and write them back to database file 3. The process continues until the start record of 200, 201 and 202 is read out, and the database file 3 is returned to the state before the transactions with transaction numbers 200, 201 and 202 were executed.

If the disk journal file 4 is not available, recovery processing similar to step S5 is performed from the tape journal file 5 (step S6). If the quick recovery file 6 is not available, recovery processing is performed using a conventional method (step S7).

〔Effect of the invention〕

As explained above, the present invention has the effect of significantly shortening recovery time because it is not necessary to read all of the final volume journal. Additionally, since a disk journal file is used, positioning time can also be reduced.

FIG. 3 is a flow diagram showing the operation of the embodiment of the present invention.

1... Terminal device, 2... Online processing process, 3
...Database file, 4...Disk di+
- Null file, 5...Tape journal file page 6...Quick recovery file, 7...Journal file, 9...Start record, 10...Before image, 11...・・・
End record.

Claims (1)

[Claims] 1. An online processing means for accessing a database file and executing a transaction, and information including update information related to an incomplete update of the database file due to a transaction being executed at the time of a system down is divided into blocks. In an online data processing device that is equipped with a journal file that is maintained chronologically in an area on a volume, and a recovery means that invalidates updated information based on a list of transactions that are being executed at the time of a system down, a predetermined number of blocks are When the system goes down, there is a quick recovery file that holds numbers assigned to blocks and numbers assigned to executed transactions, and a writing position on the journal file that is positioned according to the contents of this quick recovery file. and table creation means for creating the list based on the information read up to the writing position.