众所周知,我们的核心生产数据库通常都是在归档模式下运行的,更不用说还配置DG环境的了。开启归档,并保证所有归档不丢失,就能保证我们对数据库所做的任何修改不会丢失,归档日志可谓是恢复的根本,如果丢失归档,那么即使RMAN功能再强大,也无法对丢失的数据进行恢复。所以我们通常配置的RMAN策略就是全备+归档+控制文件自动备份。这里的归档不是指数据库创建以来生成的归档(那量也太大了),而是当进行RMAN非一致性备份时新产生的那部分归档日志,用来保证数据库可以前推到一致性状态,这样才能顺利open数据库。以下的测试只是想说明归档日志对恢复数据的重要性,并没有用到RMAN来进行恢复。
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Oracle 11G RAC 修改归档模式
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测试一:归档日志健全未丢失
--连接到Oracle,确保是运行在归档模式下
[oracle@ora10g ~]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.1.0 - Production on 8 13:46:53 2014
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> archive log list
Database log mode Archive Mode --归档模式
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 172
Next log sequence to archive 174
Current log sequence 174
SQL> set lin 130 pages 130
SQL> col name for a45
SQL> select file#,name from v$datafile;
FILE# NAME
---------- ---------------------------------------------
1 /u01/app/oracle/oradata/ora10g/system01.dbf
2 /u01/app/oracle/oradata/ora10g/undotbs01.dbf
3 /u01/app/oracle/oradata/ora10g/sysaux01.dbf
4 /u01/app/oracle/oradata/ora10g/users01.dbf
5 /u01/app/oracle/oradata/ora10g/example01.dbf
--创建测试表空间、用户、表
SQL> create tablespace zlm_test datafile '/u01/app/oracle/oradata/ora10g/zlm01.dbf' size 50m;
Tablespace created.
SQL> create user zlm identified by zlm default tablespace zlm_test;
User created.
SQL> grant connect,resource to zlm; --赋权限
Grant succeeded.
SQL> select file#,name from v$datafile;
FILE# NAME
---------- ---------------------------------------------
1 /u01/app/oracle/oradata/ora10g/system01.dbf
2 /u01/app/oracle/oradata/ora10g/undotbs01.dbf
3 /u01/app/oracle/oradata/ora10g/sysaux01.dbf
4 /u01/app/oracle/oradata/ora10g/users01.dbf
5 /u01/app/oracle/oradata/ora10g/example01.dbf
6 /u01/app/oracle/oradata/ora10g/zlm01.dbf --新增了6号文件作为测试表存放的物理介质
6 rows selected.
SQL> create table zlm.test1 as select rownum as id,object_name from dba_objects where rownum<=5;
Table created.
SQL> col object_name for a15
SQL> select * from zlm.test1;
ID OBJECT_NAME
---------- ---------------
1 ICOL$
2 I_USER1
3 CON$
4 UNDO$
5 C_COBJ#
--查看当前online日志文件状态
SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC
---------- ---------------- ---
1 INACTIVE YES
2 INACTIVE YES
3 CURRENT NO --当前日志组为3,未归档
--归档当前日志(多次)
SQL> alter system archive log current;
System altered.
SQL> alter system archive log current;
System altered.
SQL> alter system archive log current;
System altered.
这里进行了3次归档当前日志文件的操作,目的是使online日志被刷新,强制其归档,写到归档日志中去,因为我们要测试的是归档,否则恢复文件时,会自动去online日志中查找,即便是非归档模式,只要online日志还未被刷新,依旧是可以恢复的
SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC
---------- ---------------- ---
1 INACTIVE YES
2 INACTIVE YES
3 CURRENT NO --虽然看起来和刚才上一步一致,但此时其实已经把第3组online日志刷新掉了
--保险起见,再归档一次(可选)
SQL> alter system archive log current;
System altered.
SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC
---------- ---------------- ---
1 CURRENT NO
2 INACTIVE YES
3 ACTIVE YES --现在新一轮的第3组的日志也已经归档了
--一致性关闭数据库,在OS级别删除测试文件datafile 6
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> !
[oracle@ora10g ~]$ cd $ORACLE_BASE/oradata/ora10g
[oracle@ora10g ora10g]$ ll -lrth
total 1.7G
-rw-r----- 1 oracle oinstall 51M Sep 5 10:13 test02.dbf
-rw-r----- 1 oracle oinstall 301M Sep 5 10:13 test01.dbf
-rw-r----- 1 oracle oinstall 201M Sep 16 16:56 temp01.dbf
-rw-r----- 1 oracle oinstall 51M Sep 18 13:49 redo02.log
-rw-r----- 1 oracle oinstall 51M Sep 18 13:51 redo03.log
-rw-r----- 1 oracle oinstall 51M Sep 18 13:51 zlm01.dbf
-rw-r----- 1 oracle oinstall 31M Sep 18 13:51 users01.dbf
-rw-r----- 1 oracle oinstall 166M Sep 18 13:51 undotbs01.dbf
-rw-r----- 1 oracle oinstall 561M Sep 18 13:51 system01.dbf
-rw-r----- 1 oracle oinstall 271M Sep 18 13:51 sysaux01.dbf
-rw-r----- 1 oracle oinstall 51M Sep 18 13:51 redo01.log
-rw-r----- 1 oracle oinstall 101M Sep 18 13:51 example01.dbf
-rw-r----- 1 oracle oinstall 7.2M Sep 18 13:52 control03.ctl
-rw-r----- 1 oracle oinstall 7.2M Sep 18 13:52 control02.ctl
-rw-r----- 1 oracle oinstall 7.2M Sep 18 13:52 control01.ctl
[oracle@ora10g ora10g]$ rm -f zlm01.dbf
[oracle@ora10g ora10g]$ exit
exit
--重启数据库
SQL> startup
ORACLE instance started.
Total System Global Area 285212672 bytes
Fixed Size 1218992 bytes
Variable Size 88082000 bytes
Database Buffers 192937984 bytes
Redo Buffers 2973696 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 6 - see DBWR trace file
ORA-01110: data file 6: '/u01/app/oracle/oradata/ora10g/zlm01.dbf'
可以看到,此时是无法open数据库的,因为数据库文件物理上已经不存在,而在控制文件中是有记录的,这里提示的是“cannot identify/lock data file 6”,而当如果仅仅是物理上存在,数据文件头中的信息与控制文件中记录的数据文件头信息不一致时,会提示xxx文件需要恢复
--手动创建一个datafile 6
SQL> alter database create datafile 6;
Database altered.
注意,此时仅仅是创建了一个不一致的datafile 6而已,也可以通过RMAN的restore datafile 6;命令来实现,作用是一样的