6.3.5.1 Monitoring XRMEM Log Using Database Statistics and Wait Events

The following table describes database statistics that are useful for monitoring XRMEM log performance. The statistics are available in various dynamic performance views, including V$SYSSTAT, and may be displayed in the Global Activity Statistics or Instance Activity Statistics section of an AWR report.

Statistic	Description
cell xrmem log writes cell pmem log writes	The number of redo log write requests that used XRMEM log The statistic is named cell xrmem log writes in Oracle Database versions that support Oracle Exadata System Software release 23.1.0 and later. In earlier versions, it is named cell pmem log writes.

The following table describes database wait events that are useful for monitoring XRMEM log performance. The wait events are visible in various dynamic performance views, including V$SESSION, V$SYSTEM_EVENT and V$SESSION_EVENT, and may be displayed in the Wait Event sections of the AWR report.

Wait Event	Description
log file parallel write	The Oracle Database log writer (LGWR) process waits on this event when it is waiting for the completion of writes to the redo log file. Efficient use of XRMEM log is indicated by comparatively lower time waiting on this event.

The availability of a specific statistic or wait event is subject to the version of Oracle Database being used.