EventLogMode
Determines the behavior for the event log service handles an event log when the log reaches its maximum allowed size (when the event log is full).
AutoBackup = 1
Archive the log when full, do not overwrite events. The log is automatically archived when necessary. No events are overwritten.
Circular = 0
New events continue to be stored when the log file is full. Each new incoming event replaces the oldest event in the log.
Retain = 2
Do not overwrite events. Clear the log manually rather than automatically.