You can configure vCenter Server to retain events in the database for a limited period. Discarding events periodically ensures optimal performance of the database.
In new installations of vCenter Server 6.5, the event clean up option is enabled by default and the default number of days to retain event messages in the database is 30. You can change this value to the number of days that you want to retain the event messages in the database.
If you are upgrading or migrating from vCenter Server 6.7 or earlier, and you had the event cleanup option enabled, your setting to retain events is preserved after the upgrade or migration to vCenter Server 6.5.
After the retention period ends, the events are deleted from the database. However, there might be latency in the deletion of the events that are older than the configured retention setting.