10.4.4 Fall-back mode of the message log file
If the HADB server detects a shortage of free space of the disk that stores message log files, the server outputs only the available amount of message logs depending on the disk free space. This state is called fall-back mode of the message log file.
When the message log file goes into the fall-back mode, the output destination of messages is switched to the next message log file. At this time, the messages in the switching destination message log file are deleted. After switching of message log files is completed, warning message KFAA40025-W is output to the switching destination message log file and syslog. However, if the message log file on an HADB client (for Windows) goes into the fall-back mode, the KFAA40025-W message is output only to the message log file on the HADB client.
The server message log file on the HADB server might go into the fall-back mode as the result of execution of an SQL statement on an HADB client. In that case, the KFAA40025-W message is output also to the message log file on the HADB client.
- Note
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The processing of forcibly switching a message log file is executed only once when the message log file goes into the fall-back mode. The KFAA40025-W message is also output only once when the message log file goes into the fall-back mode. While a message log file is in the fall-back mode, messages are output to the switching destination message log file if it is possible. If it is not possible, messages are not output. If the size of the switching destination message log file reaches the size specified for environment variable ADBMSGLOGSIZE, messages are no longer output.
The message log file automatically returns to the normal state in the following condition. An SQL statement or command is executed when the free space of the disk that stores message log files is no less than the double of the value specified for environment variable ADBMSGLOGSIZE. After that, If the HADB server detects again a shortage of free space of the disk that stores message log files, the message log file goes again into the fall-back mode.
- Note
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For environment variable ADBMSGLOGSIZE, specify in megabytes the maximum size of a message log file. If specification of the value for ADBMSGLOGSIZE is omitted, 16 megabytes is assumed for the maximum size of a message log file.
- Checking by a command whether the message log file on the HADB server is in the fall-back mode
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To check whether the message log file on the HADB server is in the fall-back mode, execute the adbls -d srv command. Check the MSGLOG_STATUS column of the execution result.
Example:
adbls -d srv SVID STATUS START_TIME MSGLOG_STATUS 5360 ACTIVE 2017/02/02 09:31:04 FALLBACK
If FALLBACK is displayed in the MSGLOG_STATUS column, the message log file on the HADB server is in the fall-back mode. If the message log file is in the normal state, NORMAL is displayed.
For details about how to release the fall-back mode of the message log file, see 15.16.1 Releasing the message log file from fall-back mode.