DataGuard的STANDBY_ARCHIVE_DEST参数

从Oracle 10gR2开始，Oracle DataGuard技术做出了很多改进，这些改进通过极其简单的参数设置就可以实现DataGuard的环境部署。

不过在这些简化之后，是大量参数属性的引入，这甚至会使人觉得不是简化而是复杂化吧。比如对于LOG_ARCHIVE_DEST_n参数，有以下一系列属性信息，我引用一些文档连接在这里备忘：

AFFIRM and NOAFFIRM    ALTERNATE    COMPRESSION    DB_UNIQUE_NAME

DELAY    LOCATION and SERVICE    MANDATORY    MAX_CONNECTIONS

MAX_FAILURE    
NET_TIMEOUT    NOREGISTER    REOPEN

SYNC and ASYNC    
VALID_FOR

对于STANDBY_ARCHIVE_DEST参数，实际上从10gr2开始就感觉是可有可无了，在11g中，被标记为废弃，不再被支持。
这实际上是一次简化。

对于LOG_ARCHIVE_DEST_n参数，如果设置了VALID_FOR=(ALL_LOGFILES,ALL_ROLES)，那么在不定义STANDBY_ARCHIVE_DEST参数时，Oracle就会选择LOG_ARCHIVE_DEST_n参数作为归档目标。

当然也可以设置独立的LOG_ARCHIVE_DEST_n参数，设置VALID_FOR=(STANDBY_LOGFILE,*) 属性，则可以使用该路径作为备用归档路径。

当然，即使所有设置都不满足备用归档使用，Oracle会使用一个缺省路径：

SQL> show parameter standby

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
standby_archive_dest                 string      ?/dbs/arch
standby_file_management              string      MANUAL

$ORACLE_HOME/dbs/arch里是个万能的归所。
以下日志来自一个测试环境：

Sun Jun 21 02:03:12 2009
Using STANDBY_ARCHIVE_DEST parameter default value as /opt/oracle/archivelog
Redo Shipping Client Connected as PUBLIC
-- Connected User is Valid
RFS[1]: Assigned to RFS process 31987
RFS[1]: Identified database type as 'physical standby'
Sun Jun 21 02:03:12 2009
RFS LogMiner: Client disabled from further notification
RFS[1]: Successfully opened standby log 5: '/opt/oracle/oradata/eygle/stdrd2.log'
Sun Jun 21 02:03:12 2009
Fetching gap sequence in thread 1, gap sequence 37-38
Sun Jun 21 02:03:12 2009
Redo Shipping Client Connected as PUBLIC
-- Connected User is Valid
RFS[2]: Assigned to RFS process 31989
RFS[2]: Identified database type as 'physical standby'
Sun Jun 21 02:03:16 2009
Redo Shipping Client Connected as PUBLIC
-- Connected User is Valid
RFS[3]: Assigned to RFS process 31991
RFS[3]: Identified database type as 'physical standby'
Primary database is in MAXIMUM AVAILABILITY mode
Changing standby controlfile to RESYNCHRONIZATION level
Primary database is in MAXIMUM AVAILABILITY mode
Standby controlfile consistent with primary
RFS[3]: Successfully opened standby log 4: '/opt/oracle/oradata/eygle/stdrd1.log'
Sun Jun 21 02:03:16 2009
RFS[2]: Archived Log: '/opt/oracle/archivelog/1_37_689973859.dbf'
Sun Jun 21 02:03:17 2009
RFS[1]: Successfully opened standby log 5: '/opt/oracle/oradata/eygle/stdrd2.log'
Sun Jun 21 02:03:17 2009
RFS[2]: Archived Log: '/opt/oracle/archivelog/1_38_689973859.dbf'
Sun Jun 21 02:03:38 2009
Primary database is in MAXIMUM AVAILABILITY mode
Changing standby controlfile to MAXIMUM AVAILABILITY level
RFS[3]: Successfully opened standby log 4: '/opt/oracle/oradata/eygle/stdrd1.log'
Sun Jun 21 02:03:42 2009
Media Recovery Log /opt/oracle/archivelog/1_37_689973859.dbf
Media Recovery Log /opt/oracle/archivelog/1_38_689973859.dbf
Media Recovery Log /opt/oracle/archivelog/1_39_689973859.dbf
Media Recovery Log /opt/oracle/archivelog/1_40_689973859.dbf
Media Recovery Log /opt/oracle/archivelog/1_41_689973859.dbf
Media Recovery Waiting for thread 1 sequence 42 (in transit)

在Oracle 11g的文档中，已经标记出来该参数仅为向后兼容的目的保留了：

STANDBY_ARCHIVE_DEST

Property	Description
Parameter type	String
Syntax	STANDBY_ARCHIVE_DEST = filespec
Default value	Operating system-specific
Modifiable	ALTER SYSTEM
Range of values	A valid path or device name other than RAW

Note:

The STANDBY_ARCHIVE_DEST parameter is deprecated. It is retained for backward compatibility only.

STANDBY_ARCHIVE_DEST is relevant only for a standby
database in managed recovery mode. It specifies the location of archive
logs arriving from a primary database. Oracle uses STANDBY_ARCHIVE_DEST and LOG_ARCHIVE_FORMAT to fabricate the fully qualified standby log filenames and stores the filenames in the standby control file.

这个参数的历史是这样的：

Version	Parameter		Type	Modifiable
11.1.0.7	standby_archive_dest	DEPRECATED	STRING	ALTER SYSTEM (IMMEDIATE)
11.1.0.6	standby_archive_dest	DEPRECATED	STRING	ALTER SYSTEM (IMMEDIATE)
10.2.0.4	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
10.2.0.3	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
10.1.0.5	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
10.1.0.4	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
9.2.0.8	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
9.0.1.4	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)
8.1.7.4	standby_archive_dest		STRING	ALTER SYSTEM (IMMEDIATE)

-The End-