测试库检查告警日志，发现出现如下错误：

[oracle@zyx ~]$ tail -n 100 /oracle/admin/orcl/bdump/alert_orcl.log

Fri May  6 14:06:49 2016

ARC0: Media recovery disabled

Fri May  6 14:06:54 2016

ARC1: Media recovery disabled

Fri May  6 14:07:54 2016

ARC1: Media recovery disabled

Fri May  6 14:08:54 2016

ARC1: Media recovery disabled

Fri May  6 14:09:54 2016

ARC1: Media recovery disabled

Fri May  6 14:10:54 2016

ARC1: Media recovery disabled

Fri May  6 14:11:49 2016

ARC0: Media recovery disabled

Fri May  6 14:11:54 2016

ARC1: Media recovery disabled

Fri May  6 14:12:54 2016

ARC1: Media recovery disabled

原因：

oracle 9i执行alter database noarchivelog;后automatic archivel是不会disabled，需要执行下archive log stop;后才行。

但是下次启动后，告警日志又会出现该错误信息，既automatic archivel有时enabled值。
因此还需要修改参数log_archive_start=false值。

oracle11g执行alter database noarchivelog;后会自动将automatic archivel 修改为disabled

处理：

SQL> archive log list;

Database log mode              No Archive Mode

Automatic archival             Enabled

Archive destination            /u05/arch

Oldest online log sequence     1685

Current log sequence           1687

从这里可以看出，数据库处于非归档模式

但是如果log_archive_start=true，这样会导致归档进程自动启动(ARCn),因为数据库设置为非归档模式，从而导致该进程启动后，又自己关闭

SQL> show parameter archive_start

NAME                                 TYPE                             VALUE

------------------------------------ -------------------------------- ------------------------------

log_archive_start                    boolean                          TRUE

SQL>

SQL> archive log stop

Statement processed.

SQL> alter system set log_archive_start=false scope=spfile;

System altered.

查看告警日志，未再出现ARC1: Media recovery disabled

[oracle@zyx ~]$ tail -n 100 /oracle/admin/orcl/bdump/alert_orcl.log

Fri May  6 16:46:54 2016

ARC1: Media recovery disabled

Fri May  6 16:47:54 2016

ARC1: Media recovery disabled

Fri May  6 16:48:23 2016

Archive Log Stop

Archiving is disabled

Shutting down archive processes

Archiving is disabled

Fri May  6 16:48:23 2016

ARCH shutting down

Fri May  6 16:48:23 2016

ARCH shutting down

Fri May  6 16:48:23 2016

ARC0: Archival stopped

Fri May  6 16:48:23 2016

ARC1: Archival stopped

Fri May  6 16:49:39 2016

ALTER SYSTEM SET log_archive_start=FALSE SCOPE=SPFILE;

Fri May  6 16:52:38 2016

Thread 1 advanced to log sequence 1688