16.12 System log operations (when the multi-node function is being used)
When the multi-node function is being used, there is only one system log file for all nodes, and it is controlled by the HADB server on the master node. The HADB server on the master node outputs the operation history information of the HADB servers on all nodes, as well as the database update history information, as system logs to the system log file.
System log files are created in the file system that is mounted to the /ADBSYS/ADBSLG directory under the master node's DB directory.
For details about the system log, see (2) System log in 2.11.1 Recovery flow based on a restart.
- ▪ When a master node switchover occurs
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Carry over the system log managed by the HADB server of the old master node, to the HADB server of the new master node. The HADB server of the new master node uses the carried over system log to perform recovery processing (rollback) on update processing that had been running on the master node.
If a master node switchover occurs, the file system storing the system log is unmounted from the pre-switchover master node. Then, the file system is mounted to the /ADBSYS directory under the new master node's DB directory. HA Monitor performs these unmount and mount processes automatically.