Prepare the Mining Database to Accept Redo from the Source Databases

Because redo data is being accepted in the standby redo logs of the downstream mining database, the appropriate number of correctly sized standby redo logs must exist. If you did not configure the standby logs, see Configuring a Downstream Mining Database.

At the downstream mining database, set the second archive log destination in the LOG_ARCHIVE_DEST_n initialization parameter as shown in the following example. This is needed to handle archive standby redo logs.
```
ALTER SYSTEM SET
LOG_ARCHIVE_DEST_2='LOCATION=/home/arc_dest/srl_dbms3
VALID_FOR=(STANDBY_LOGFILE,PRIMARY_ROLE)'
```
Enable the LOG_ARCHIVE_DEST_STATE_2 initialization parameter that corresponds with the LOG_ARCHIVE_DEST_2 parameter as shown in the following example.
```
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE 
```
Set DG_CONFIG at the downstream mining database to accept redo data from all of the source databases.
```
ALTER SYSTEM SET LOG_ARCHIVE_CONFIG='DG_CONFIG=(dbms1, dbms2, dbms3, dbmscap)' 
```