Search notes:

Oracle database: archiving mode

An Oracle database is either in
The current mode can be determined with 
select
   name,
   dbid,
   log_mode
from
   gv$database

Put database into archivelog mode

sqlplus / as sysdba
SQL> shutdown immediate
Make a ­ development/databases/Oracle/adminstration/backup-recovery/backup[backup]. 
sqlplus / as sysdba
SQL> alter database archivelog;
SQL> alter database open;
Change initialization parameters log_archive_dest_n. 
sqlplus / as sysdba
SQL> shutdown immediate
Make another ­ development/databases/Oracle/adminstration/backup-recovery/backup[backup].

Queries

select * from gv$archive_dest;
select * from v$parameter where name like 'log_archive_dest%';
select * from gv$archive_processes;

ORA-00257 Archiver error. Connect AS SYSDBA only until resolved

Solution: make sure that

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