RAC环境下的归档模式切换与单实例稍有不同，主要是共享存储所产生的差异。在这种情况下，我们可以将RAC数据库切换到非集群状态下，仅仅在一个实例上来实施归档模式切换即可完成RAC数据库的归档模式转换问题。本文主要描述了由非归档模式切换到归档模式，而由非归档切换的归档步骤相同，不再赘述。
1、主要步骤：
备份spfile，以防止参数修改失败导致数据库无法启动
修改集群参数cluster_database为false
启动单实例到mount状态
将数据库置于归档模式(alter database archivelog/noarchivelog)
修改集群参数cluster_database为true
关闭单实例
启动集群数据库
2、环境
oracle@bo2dbp:~> cat /etc/issue
Welcome to SUSE Linux Enterprise Server 10 SP3 (x86_64) - Kernel \r (\l).
oracle@bo2dbp:~> sqlplus -v
SQL*Plus: Release 10.2.0.3.0 - Production
使用asm存储方式存放归档日志
3、修改集群数据库到归档模式
oracle@bo2dbp:~> export ORACLE_SID=ora10g1
oracle@bo2dbp:~> sqlplus / as sysdba
SQL*Plus: Release 10.2.0.3.0 - Production on Mon Dec 24 16:53:18 2012
Copyright (c) 1982, 2006, Oracle. All Rights Reserved.
Connected to:
Oracle Database 10g Release 10.2.0.3.0 - 64bit Production
With the Real Application Clusters option
SQL> archive log list; -->查看当前数据库的归档模式
Database log mode No Archive Mode -->非归档模式
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 59
Current log sequence 60
SQL> select instance_name,host_name,status from gv$instance;
INSTANCE_NAME HOST_NAME STATUS
---------------- -------------------- ------------
ora10g1 bo2dbp OPEN
ora10g2 bo2dbs OPEN
SQL> show parameter cluster -->查看集群的参数,cluster_database为true表示为集群数据库，否则，非集群数据库
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
cluster_database boolean TRUE
cluster_database_instances integer 2
cluster_interconnects string
SQL> create pfile='/u01/oracle/db/dbs/ora10g_robin.ora' from spfile; -->先备份spfile
File created.
SQL> alter system set cluster_database=false scope=spfile sid='*'; -->修改为非集群数据库，该参数为静态参数，需要使用scope=spfile
System altered.
oracle@bo2dbp:~> srvctl stop database -d ora10g -->关闭数据库
oracle@bo2dbp:~> srvctl start instance -d ora10g -i ora10g1 -o mount -->启动单个实例到mount状态
oracle@bo2dbp:~> sqlplus / as sysdba
SQL> select instance_name,status from v$instance;
INSTANCE_NAME STATUS
---------------- ------------
ora10g1 MOUNTED
SQL> alter database archivelog; -->改变数据库到归档模式
Database altered.
SQL> alter system set cluster_database=true scope=spfile sid='*'; -->在将数据库改为集群模式
System altered.
SQL> ho srvctl stop instance -d ora10g -i ora10g1 -->关闭当前实例
SQL> ho srvctl start database -d ora10g -->启动集群数据库
SQL> archive log list;
ORA-03135: connection lost contact
SQL> conn / as sysdba
Connected.
SQL> archive log list; -->查看归档模式
Database log mode Archive Mode -->已经处于归档模式
Automatic archival Enabled -->自动归档
Archive destination USE_DB_RECOVERY_FILE_DEST -->归档位置为参数DB_RECOVERY_FILE_DEST的值
Oldest online log sequence 60 -->下面是sequence相关信息
Next log sequence to archive 61
Current log sequence 61
SQL> show parameter db_recovery_file
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string +REV
db_recovery_file_dest_size big integer 2G
4、归档验证
SQL> select inst_id,name,thread#,sequence#,status from gv$archived_log; -->当前无任何归档日志
no rows selected
SQL> alter system switch logfile; -->在实例1上进行归档
System altered.
SQL> col name format a65
SQL> select inst_id,name,thread#,sequence#,status from gv$archived_log; -->查看到sequence为61的日志已经归档
INST_ID NAME THREAD# SEQUENCE# S
---------- ----------------------------------------------------------------- ---------- ---------- -
1 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61
SQL> select name,thread#,sequence#,status from v$archived_log; -->下面是从实例级别的视图来查看
NAME THREAD# SEQUENCE# S
----------------------------------------------------------------- ---------- ---------- -
+REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61 A
SQL> conn system/oracle@ora10g2 -->连接到实例2
Connected.
SQL> show parameter instance_name;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
instance_name string ora10g2
SQL> alter system switch logfile; -->在实例2上进行归档
System altered.
SQL> select inst_id,name,thread#,sequence#,status from gv$archived_log;
-->可以看到sequence为43的日志已经归档
-->注意这个视图查询时同一个归档日志除了出现在自身实例中外,对另外的实例也是可见的
INST_ID NAME THREAD# SEQUENCE# S
---------- ----------------------------------------------------------------- ---------- ---------- -
1 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61 A
1 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_43.458.802893283 2 43 A
2 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61 A
2 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_43.458.802893283 2 43 A
-->查看日志的状态
-->注意这个v$log视图将两个实例上的组及状态都显示出来了
-->在这里用thread#来区分，thread#为1表示实例1上的日志组有1,2,且1处于current状态.thread#2类似.
SQL> select * from v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- ---------
1 1 62 52428800 2 NO CURRENT 4314741 24-DEC-12
2 1 61 52428800 2 YES ACTIVE 4312116 24-DEC-12
3 2 43 52428800 2 YES ACTIVE 4312300 24-DEC-12
4 2 44 52428800 2 NO CURRENT 4315097 24-DEC-12
-->Author: Robinson
-->归档当前日志,注意该命令在单实例下等同于alter system switch logfile
-->在rac环境下则不同，那就是所有实例上的current日志都将会被归档
SQL> alter system archive log current;
System altered.
-->下面的查询正好验证了上面的描述
-->日志62与44正是刚刚上面的命令同时产生的归档日志
SQL> select inst_id,name,thread#,sequence#,status from gv$archived_log;
INST_ID NAME THREAD# SEQUENCE# S
---------- ----------------------------------------------------------------- ---------- ---------- -
2 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61 A
2 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_43.458.802893283 2 43 A
2 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_44.456.802894343 2 44 A
2 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_62.457.802894341 1 62 A
1 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_61.459.802892953 1 61 A
1 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_43.458.802893283 2 43 A
1 +REV/ora10g/archivelog/2012_12_24/thread_2_seq_44.456.802894343 2 44 A
1 +REV/ora10g/archivelog/2012_12_24/thread_1_seq_62.457.802894341 1 62 A
8 rows selected.