It's not really good to read the doc carefully.
SQL> shutdown immediate
The database has been closed.
The database has been detached.
The Oracle routine has been disabled.
SQL> startup mount
The ORACLE routine has been started.
Total System Global Area 104857600 bytes
Fixed Size 1247540 bytes
Variable Size 96470732 bytes
Database Buffers 4194304 bytes
Redo Buffers 2945024 bytes
The database has been loaded.
-- Enable manual archiving
SQL> alter database archivelog manual;
The database has been changed.
SQL> select log_mode from v $ database;
LOG_MODE
------------
MANUAL
SQL> alter database open;
The database has been changed.
SQL> show parameter log_archive_max_processes
NAME TYPE VALUE
-----------------------------------------------------------------------------
Log_archive_max_processes integer 4
-- The archiving process is up.
SQL> select * from v $ archive_processes where status = 'active ';
Process status LOG_SEQUENCE STAT
------------------------------------
0 ACTIVE 0 IDLE
1 ACTIVE 0 IDLE
2 ACTIVE 0 IDLE
3 ACTIVE 0 IDLE
4 ACTIVE 0 IDLE
-- Enable automatic archiving"
SQL> archive log list;
Database Log mode archiving Mode
Enable automatic archiving
Archiving end point USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 111
Next archive log sequence 112
Current Log sequence 112
SQL> alter system switch logfile;
The system has been changed.
SQL> alter system switch logfile;
-- It hangs...
-- ==============================================
Open another session:
SQL> alter system archive log current;
The system has been changed.
SQL>