在ASM单机环境下，开启归档的最简单的方法。
环境：oracle11g  11.2.0.4

登陆sqlplus
[oracle@udevasm ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Thu Jun 8 18:20:41 2017

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

要把Oracle数据库给启动到Open状态

SQL> startup
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size            2260088 bytes
Variable Size          331350920 bytes
Database Buffers      729808896 bytes
Redo Buffers            5517312 bytes
Database mounted.
Database opened.

查看ASM空间使用率
SQL>  select group_number,name,total_mb,free_mb from v$asm_diskgroup;

GROUP_NUMBER NAME                  TOTAL_MB      FREE_MB
------------ ------------------------------ ---------- ----------
       1 DGDATA01                 22520          260
       2 DGDATA02                 20472        14132
       3 DGRECOVERY              21500        21420
       4 DGSYSTEM                 20472        20392
       5 GRID1                 10232        10144

查看归档状态
SQL> archive log list;
Database log mode           No Archive Mode
Automatic archival           Disabled
Archive destination           /oracle/app/oracle/product/11.2.0/dbs/arch
Oldest online log sequence     9
Current log sequence           14

SQL> show user
USER is "SYS"

关库，或使用命令：shutdown immediate来关闭
SQL> shutdown    immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.

启库到mount
SQL> startup mount;
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size            2260088 bytes
Variable Size          331350920 bytes
Database Buffers      729808896 bytes
Redo Buffers            5517312 bytes
Database mounted.

查看当前节点的状态
SQL> select status from gv$instance;

STATUS
------------
MOUNTED

为节点开启归档，开启归档
SQL> alter database archivelog;

Database altered.

查看归档状态，发现归档日志路径不对，并不是默认的路径在ASM中的路径

SQL> archive log list;
Database log mode           Archive Mode
Automatic archival           Enabled
Archive destination           /oracle/app/oracle/product/11.2.0/dbs/arch
Oldest online log sequence     9
Next log sequence to archive   14
Current log sequence           14

修改归档路径

SQL>  ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=+DGRECOVERY/' SCOPE=SPFILE SID='udevasm'; 

查看当前修改后路径

SQL> archive log list;
Database log mode           Archive Mode
Automatic archival           Enabled
Archive destination           +DGRECOVERY/arc
Oldest online log sequence     9
Next log sequence to archive   14
Current log sequence           14

节点启库
SQL> alter database open;

Database altered.

SQL> select status from v$instance;

STATUS
------------
OPEN

来看一下，归档路径的信息，默认是直接指向了ASM中的路径
SQL> show parameter log_archive_dest;

NAME                     TYPE     VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest             string
log_archive_dest_1             string     LOCATION=+DGRECOVERY/ARC
log_archive_dest_10             string
log_archive_dest_11             string
log_archive_dest_12             string
log_archive_dest_13             string
log_archive_dest_14             string
log_archive_dest_15             string
log_archive_dest_16             string
log_archive_dest_17             string
log_archive_dest_18             string

到ASM下看一下归档文件
ASMCMD> lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  4194304     22520      260                0             260              0             N  DGDATA01/
MOUNTED  EXTERN  N         512   4096  4194304     20472    14132                0           14132              0             N  DGDATA02/
MOUNTED  EXTERN  N         512   4096  4194304     21500    21420                0           21420              0             N  DGRECOVERY/
MOUNTED  EXTERN  N         512   4096  4194304     20472    20392                0           20392              0             N  DGSYSTEM/
MOUNTED  EXTERN  N         512   4096  4194304     10232    10144                0           10144              0             N  GRID1/

SMCMD> cd 2017_06_08/
ASMCMD> l
thread_1_seq_14.256.946154499
thread_1_seq_15.257.946154499
thread_1_seq_16.258.946154499
thread_1_seq_17.259.946154499
thread_1_seq_18.260.946154501
thread_1_seq_19.261.946154523
thread_1_seq_20.262.946154571