HiRDB parallel server configuration

Database recovery in the event of an error: If a database error occurs in the operating environment in which system logs are unloaded, the database is recovered from a backup copy and the unload log files that contain system log information collected since the backup was made. For details on the database recovery procedure, see 21. Database Recovery Procedures.

System log for a front-end server

System log information for a front-end server need not be unloaded because it is not required for database recovery. The specification pd_log_unload_check=N in the front-end server definition releases checking of system log file unload status for the front-end server. This eliminates the need to unload the front-end server's system log file. When pd_log_unload_check=N is not specified, one of the following actions must be taken for a file in unload wait status at the front-end server:

Execute the pdlogunld command to unload the system log information and place the file in unload completed status
Execute the pdlogchg command to forcibly change the file's status to unload completed

Example: The following figure shows the procedure for unloading a system log in a HiRDB parallel server configuration.; Figure 3-2 Procedure for unloading a system log (HiRDB parallel server configuration)

Notes: #1: 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.; #2: Perform Steps 1 to 3 each time system log file swapping occurs.

Organization of this subsection: (1) Check the file status when the system log files are swapped; (2) Unload the system log; (3) Check the status of the system log file; (4) Swap the system log files; (5) Make a backup; (6) Check the status of the system log file; (7) Unload the system log

(1) Check the file status when the system log files are swapped

When a system log file becomes full, it is swapped with another file. When system log file swapping occurs, the KFPS01221-I and KFPS01222-I messages are output to the message log file and the syslogfile. The pdlogls command can be used to check the status of the system log file:

 
pdlogls -d sys -s bes1

[Figure]

Explanation

Because the log01 file has been filled with the system log, the system log output destination changes from log01 to log02 (the system log files are swapped). As a result, log01 is placed in the following statuses:

Overwrite disabled
Unload wait

(2) Unload the system log

(3) Check the status of the system log file

The pdlogls command is used to check the status of the system log file (log01):

 
pdlogls -d sys -s bes1

[Figure]

Explanation

Once the system log has been unloaded, the file status changes from unload wait to unload completed.
When the system log files are swapped, synchronization point dump validation processing is executed. When the synchronization point dumps have been validated, the file status changes from overwrite disabled to overwrite enabled.
As a result, the file status changes from unswappable target to swappable target.

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

(4) Swap the system log files

Before a backup copy is made, the pdlogswap command is used to swap the system log files; in this example, the system log file for a back-end server (bes1) is swapped because the RDAREAs in bes1 are to be backed up.

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 -s bes1 -w

(5) Make a backup

The pdcopy command (database copy utility) is used to back up in units of servers. For details about making backups, see 6. Backup Procedures.

 
pdcopy -m /rdarea/mast/mast01 -M r -s bes1 -b /pdcopy/backup01

Explanation: -m: Specifies the name of the first HiRDB file in the master directory RDAREA.; -M: Specifies the backup acquisition mode (r or s).; -s: Specifies that all RDAREAs on back-end server bes1 are to be backed up.; -b: Specifies the name of the backup file.

Important: If the backup copy made in this step is used subsequently to recover the RDAREAs, the unload log files containing system log information subsequent to this current file are used as input to the database recovery utility.

3.2.2 HiRDB parallel server configuration

(1) Check the file status when the system log files are swapped

(2) Unload the system log

(3) Check the status of the system log file

(4) Swap the system log files

(5) Make a backup

(6) Check the status of the system log file

(7) Unload the system log