How to construct multi physical stdbys with different protection mode in the the DG environment
DG Environment:
one primary and two physical standbys. All of them are single node.
prmary 's unique name: tstdb1
1st standby's unique name: tstdb1_stdby1
2st standby's unique name: tstdb1_stdby2
---on tstdb1, required parameters for DG is configured like the following
log_archive_dest_1='location=USE_DB_RECOVERY_FILE_DEST valid_for=(all_logfiles,all_roles) db_unique_name=tstdb1'
log_archive_dest_2='service=tstdb1_stdby1 SYNC affirm valid_for=(online_logfiles,primary_roles) db_unique_name=tstdb1_stdby1'
log_archive_dest_3='service=tstdb1_stdby2 SYNC affirm valid_for=(online_logfiles,primary_roles) db_unique_name=tstdb1_stdby2'