oracle 配置归档冗余

--创建本地归档目录
[oracle@XLJ181 admin]$ mkdir -p /u01/app/oracle/archive2
[oracle@XLJ181 admin]$ mkdir -p /u01/app/oracle/archive3
--配置log_archive_dest_n参数
SYS@cams> alter system set log_archive_duplex_dest='';
  
System altered.
  
SYS@cams> alter system set log_archive_dest='';
  
System altered.
  
SYS@cams> alter system set log_archive_dest_1='LOCATION=USE_DB_RECOVERY_FILE_DEST';
  
System altered.
  
SYS@cams> alter system set log_archive_dest_2='LOCATION=/u01/app/oracle/archive2';
  
System altered.
  
SYS@cams> alter system set log_archive_dest_3='LOCATION=/u01/app/oracle/archive3';
  
System altered.
需要注意置空的顺序，以免出现如下错误

SYS@cams> alter system set log_archive_dest='';
alter system set log_archive_dest=''
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16022: LOG_ARCHIVE_DEST cannot be NULL because LOG_ARCHIVE_DUPLEX_DEST is
non-NULL
需要将LOG_ARCHIVE_DEST和LOG_ARCHIVE_DUPLEX_DEST参数置空，以免出现如下问题：

SYS@cams> alter system set log_archive_dest_1='LOCATION=USE_DB_RECOVERY_FILE_DEST';
alter system set log_archive_dest_1='LOCATION=USE_DB_RECOVERY_FILE_DEST'
*
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-16019: cannot use LOG_ARCHIVE_DEST_1 with LOG_ARCHIVE_DEST or
LOG_ARCHIVE_DUPLEX_DEST
--切换日志，触发写归档日志
SYS@cams> alter system switch logfile;
  
System altered.
查看新生成的归档日志文件，显然新生成的归档大小和文件名一致。两份归档日志互为冗余。

[oracle@XLJ181 admin]$ ll /u01/app/oracle/archive2
total 5440
-rw-r----- 1 oracle oinstall 4416512 Dec 18 19:09 1_27_994950965.dbf
-rw-r----- 1 oracle oinstall 1148416 Dec 18 19:23 1_28_994950965.dbf
[oracle@XLJ181 admin]$ ll /u01/app/oracle/archive3
total 5440
-rw-r----- 1 oracle oinstall 4416512 Dec 18 19:09 1_27_994950965.dbf
-rw-r----- 1 oracle oinstall 1148416 Dec 18 19:23 1_28_994950965.dbf
查看trace日志，看到错误提示，提示DB_RECOVERY_FILE_DEST未设置值

Tue Dec 18 19:23:59 2018
Errors in file /u01/app/oracle/diag/rdbms/cams/cams/trace/cams_arc3_29341.trc:
ORA-19801: initialization parameter DB_RECOVERY_FILE_DEST is not set
Errors in file /u01/app/oracle/diag/rdbms/cams/cams/trace/cams_arc3_29341.trc:
ORA-16032: parameter LOG_ARCHIVE_DEST_1 destination string cannot be translated
ORA-19801: initialization parameter DB_RECOVERY_FILE_DEST is not set
Archived Log entry 25 added for thread 1 sequence 28 ID 0x9e3b45f3 dest 2:
Archived Log entry 26 added for thread 1 sequence 28 ID 0x9e3b45f3 dest 3:
为DB_RECOVERY_FILE_DEST参数配置数值，切换日志

SYS@cams> alter system set DB_RECOVERY_FILE_DEST='/u01/app/oracle/fast_recovery_area';              
  
System altered.
  
SYS@cams> alter system switch logfile;
  
System altered.
  
SYS@cams> alter system switch logfile;
  
System altered.
查看trace日志信息，最后可看到同时写入了3个归档路径

Tue Dec 18 19:27:58 2018
**********************************************************
WARNING: Files may exists in db_recovery_file_dest
that are not known to the database. Use the RMAN command
CATALOG RECOVERY AREA to re-catalog any such files.
If files cannot be cataloged, then manually delete them
using OS command.
One of the following events caused this:
1. A backup controlfile was restored.
2. A standby controlfile was restored.
3. The controlfile was re-created.
4. db_recovery_file_dest had previously been enabled and
   then disabled.
**********************************************************
ALTER SYSTEM SET db_recovery_file_dest='/u01/app/oracle/fast_recovery_area' SCOPE=BOTH;
Tue Dec 18 19:27:58 2018
db_recovery_file_dest_size of 10240 MB is 5.63% used. This is a
user-specified limit on the amount of space that will be used by this
database for recovery-related files, and does not reflect the amount of
space available in the underlying filesystem or ASM diskgroup.
Tue Dec 18 19:28:01 2018
Thread 1 cannot allocate new log, sequence 30
Private strand flush not complete
  Current log# 2 seq# 29 mem# 0: /u01/app/oracle/oradata/cams/redo02.log
Thread 1 advanced to log sequence 30 (LGWR switch)
  Current log# 3 seq# 30 mem# 0: /u01/app/oracle/oradata/cams/redo03.log
Tue Dec 18 19:28:01 2018
Archived Log entry 27 added for thread 1 sequence 29 ID 0x9e3b45f3 dest 2:
Archived Log entry 28 added for thread 1 sequence 29 ID 0x9e3b45f3 dest 3:
Tue Dec 18 19:33:38 2018
Thread 1 cannot allocate new log, sequence 31
Private strand flush not complete
  Current log# 3 seq# 30 mem# 0: /u01/app/oracle/oradata/cams/redo03.log
Thread 1 advanced to log sequence 31 (LGWR switch)
  Current log# 1 seq# 31 mem# 0: /u01/app/oracle/oradata/cams/redo01.log
Tue Dec 18 19:33:39 2018
Expanded controlfile section 11 from 28 to 62 records
Requested to grow by 34 records; added 2 blocks of records
Archived Log entry 29 added for thread 1 sequence 30 ID 0x9e3b45f3 dest 1:
Archived Log entry 30 added for thread 1 sequence 30 ID 0x9e3b45f3 dest 2:
Archived Log entry 31 added for thread 1 sequence 30 ID 0x9e3b45f3 dest 3: