3.3.1 HiRDB/Single Server

Backup acquisition units
A backup is made of the entire system (all RDAREAs). The obtained log point information file is used to release the system log files.
Backup acquisition interval
A backup should be made daily at a specified time.
The backup acquisition interval depends on the system log file size; the larger the system log file size, the longer the backup acquisition interval can be. The backup acquisition interval should be set so that the system will never run out of files in swappable target status.
Number of system log files
The total number of system log files should be more than double the number of system log files needed for one day.
For example, if two system log files are used per day, no fewer than four system log files should be provided.
Database recovery in the event of an error
If a database error occurs during operation without unloading the system log, the database must be recovered from its backup copy and the unload log files that contain system log information obtained since the backup was made. For details on the database recovery procedure, see 19. Database Recovery Procedures.
Example
Figure 3-4 shows the procedure for operation without unloading the system log at a HiRDB/Single Server.

Figure 3-4 Procedure for operation without unloading the system log (HiRDB/Single Server)

[Figure]
Note
The numbers to the left of the process boxes correspond to the paragraph numbers of the explanations on the following pages. For example, step 5 is explained in paragraph (5) below.
Organization of this subsection
(1) Swap the system log files
(2) Check the status of the system log file
(3) Make a backup
(4) Release the system log file
(5) Check the status of the system log file
(6) Check for files in swappable target status

(1) Swap the system log files

Before a backup copy is made, the pdlogswap command is used to swap the system log files.

System log files are swapped in order to physically separate the system logs needed for database restoration. The system log files storing the system log information needed for database restoration are those that become primary from this point on:

pdlogswap -d sys -w

(2) Check the status of the system log file

The pdlogls command is used to check the status of the system log file:

pdlogls -d sys

[Figure]

Explanation
  • Files log01 and log02 were used today, so these two files are in unload wait status.
  • Synchronization point dumps have been validated because the system log files were swapped by the pdlogswap -w command. In this manner, files log01 and log02 are placed in overwrite enabled status.

(3) Make a backup

The pdcopy command (database copy utility) is used to back up all RDAREAs; log point information is also obtained by specifying the -z option:

pdcopy -m /rdarea/mast/mast01 -M r -a -b /pdcopy/backup01
-z /pdcopy/logpoint01

Explanation
-m: Specifies the name of the first HiRDB file in the master directory RDAREA.
-M: Specifies r as the backup acquisition mode.
-a: Specifies that all RDAREAs are to be backed up.
-b: Specifies the name of the backup file.
-z: Specifies the name of the log point information file.
In the event of an error in the log point information file
If an error occurs in the log point information file, it must be re-created using the backup file obtained in this step; the pdrstr -z command (database recovery utility) is used to re-create a log point information file:

pdrstr -b /pdcopy/backup01 -z /pdcopy/logpoint01

(4) Release the system log file

The pdlogchg command is used to release the system log files that predate the log point (log01 and log 02); the log point information file obtained in step (3) is specified in the -z option:

pdlogchg -z /pdcopy/logpoint01

(5) Check the status of the system log file

The pdlogls command is used to check the status of the system log file:

pdlogls -d sys

[Figure]

Explanation
  • Once the system log file has been released, the file status changes from unload wait to unload completed.
  • The file is now in overwrite enabled and unload completed status; therefore, it changes from unswappable target to swappable target.

(6) Check for files in swappable target status

The pdlogls command is used to check for files in swappable target status:

pdlogls -d sys

Important
If system log file swapping occurs when there is no file in swappable target status, the HiRDB/Single Server terminates abnormally. For this reason, the HiRDB administrator must ensure that there is always available a file in swappable target status.
When there is no file in swappable target status, HiRDB outputs the KFPS01224-I message to the message log file and the syslogfile.