Enable/Disable Archive Log Mode

Verify database log mode

sqlplus / as sysdba
archive log list

Non-RAC database

Enable archive log

shutdown immediate;
startup mount;
alter database archivelog;
alter database open;

Disable archive log

shutdown immediate;
startup mount;
alter database noarchivelog;
alter database open;

RAC database

Enable archive log

srvctl stop database -d orcl
srvctl start database -d orcl -o mount
 
sqlplus / as sysdba
alter database archivelog;
EXIT;

srvctl stop database -d orcl
srvctl start database -d orcl 

Disable archive log

srvctl stop database -d orcl
srvctl start database -d orcl -o mount
 
sqlplus / as sysdba
alter database noarchivelog;
EXIT;

srvctl stop database -d orcl
srvctl start database -d orcl