RMAN_BACKUP_LOOKBACK_OVERRIDE
Valid Values: Y or N (Default = N)
Scope: This parameter can be set at the Data Collector level.
When this advanced parameter is set to "Y" the value set for RMAN_BACKUP_LOOKBACK_DAYS is used ignoring any previous collection date. This can be used to collect historical data.
After running a collection with this advanced parameter set to "Y" ensure that it is reset back to "N" to avoid excessively-long collection cycles.