Standby roll forwad by using rman incremental backup

When the physical standby database lags far behind the primary database, using rman incremental backup is better than applying tons of archived logs. Here are steps.
Step1.Standby database: check the current scn
SQL> select current_scn from v$database;
CURRENT_SCN
—————————————-
788209520

Step2. Primary database: incremental backup from the scn.
run {
allocate channel dev_0 device type disk;
allocate channel dev_1 device type disk;
allocate channel dev_2 [...]