归档模式下丢失或损坏一个数据文件

1. OS备份方案
在归档方式下损坏或丢失一个数据文件,如果存在相应的备份与该备份以来的归档日志,恢复还是比较简单的,可以作到尽量少的Down机时间,并能作到数据库的完全恢复。

(1) 连接数据库,创建测试表并插入记录

SQL> connect internal/password as sysdba;
Connected.
SQL> create table test(a int) tablespace users;
Table created
SQL> insert into test values(1);
1 row inserted
SQL> commit;
Commit complete

(2) 备份数据库

SQL> @hotbak.sql 或在DOS下 svrmgrl @hotbak.sql

(3) 继续在测试表中插入记录

SQL> insert into test values(2);
1 row inserted
SQL> commit;
Commit complete
SQL> select * from test;
                         A
---------------------------------------
                         1
                         2
SQL> alter system switch logfile;
System altered.
SQL> alter system switch logfile;
System altered.

(4) 关闭数据库,模拟丢失数据文件

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down
C:\>del D:\ORACLE\ORADATA\TEST\USERS01.DBF
模拟媒体毁坏

(5) 启动数据库错误,脱机该数据文件

SQL> startup
ORACLE instance started.

Total System Global Area  102020364 bytes
Fixed Size                    70924 bytes
Variable Size              85487616 bytes
Database Buffers           16384000 bytes
Redo Buffers                  77824 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 3 - see DBWR trace file
ORA-01110: data file 3: 'D:\ORACLE\ORADATA\TEST\USERS01.DBF'
还可以查看报警文件(见上一个恢复案例)或动态视图v$recover_file
如SQL> select * from v$recover_file;

     FILE# ONLINE  ERROR                 CHANGE# TIME
---------- ------- ------------------ ---------- -----------
         3 ONLINE                        1013500 2003-05-07

脱机数据文件
SQL> alter database datafile 3 offline drop;
Database altered.

(6) 打开数据库,拷贝备份回来(restore),恢复(recover)该数据文件,并联机

SQL> alter database open;
Database altered.
拷贝备份从备份处
copy d:\databak\ users01.dbf d:\oracle\oradata\test;
恢复该数据文件
SQL> recover datafile 3;
ORA-00279: change 1053698 generated at 05/07/2003 17:51:26 needed for thread 1
ORA-00289: suggestion : D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00304.ARC
ORA-00280: change 1053698 for thread 1 is in sequence #304

Specify log: {=suggested | filename | AUTO | CANCEL}
AUTO
ORA-00279: change 1053701 generated at 05/07/2003 17:51:39 needed for thread 1
ORA-00289: suggestion : D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00305.ARC
ORA-00280: change 1053701 for thread 1 is in sequence #305
ORA-00278: log file 'D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00304.ARC' no
longer needed for this recovery

Log applied.
Media recovery complete.
恢复成功,联机该数据文件
SQL> alter database datafile 3 online;
Database altered.

(7) 检查数据库的数据(完全恢复)

SQL> select * from test;
                         A
---------------------------------------
                         1
                         2

说明:
1、采用热备份,需要运行在归档模式下,可以实现数据库的完全恢复,也就是说,从备份后到数据库崩溃时的数据都不会丢失。
2、可以采用全备份数据库的方式备份,对于特殊情况,也可以只备份特定的数据文件,如只备份用户表空间(一般情况下对于某些写特别频繁的数据文件,可以单独加大备份频率)
3、如果在恢复过程中,发现损坏的是多个数据文件,即可以采用一个一个数据文件的恢复方法(第5步中需要对数据文件一一脱机,第6步中需要对数据文件分别恢复),也可以采用整个数据库的恢复方法。
4、如果是系统表空间的损坏,不能采用此方法

2. RMAN备份方案
RMAN也可以进行联机备份,而且备份与恢复方法将比OS备份更简单可靠。
(1) 连接数据库,创建测试表并插入记录

SQL> connect internal/password as sysdba;
Connected.

SQL> create table test(a int) tablespace users;
Table created
SQL> insert into test values(1);
1 row inserted
SQL> commit;
Commit complete

(2) 备份数据库表空间users

C:\>rman
Recovery Manager: Release 8.1.6.0.0 - Production
RMAN> connect rcvcat rman/rman@back
RMAN-06008: connected to recovery catalog database
RMAN> connect target internal/virpure
RMAN-06005: connected to target database: TEST (DBID=1788174720)

RMAN> run{
2> allocate channel c1 type disk;
3> backup tag 'tsuser' format 'd:\backup\tsuser_%u_%s_%p'
4> tablespace users;
5> release channel c1;
6> }

RMAN-03022: compiling command: allocate
RMAN-03023: executing command: allocate
RMAN-08030: allocated channel: c1
RMAN-08500: channel c1: sid=16 devtype=DISK

RMAN-03022: compiling command: backup
RMAN-03025: performing implicit partial resync of recovery catalog
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete
RMAN-03023: executing command: backup
RMAN-08008: channel c1: starting full datafile backupset
RMAN-08502: set_count=5 set_stamp=494177612 creation_time=16-MAY-03
RMAN-08010: channel c1: specifying datafile(s) in backupset
RMAN-08522: input datafile fno=00003 name=D:\ORACLE\ORADATA\TEST\USER01.DBF
RMAN-08013: channel c1: piece 1 created
RMAN-08503: piece handle=D:\BACKUP\TSUSER_05EN93AC_5_1 comment=NONE
RMAN-08525: backup set complete, elapsed time: 00:00:01
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete
RMAN-03022: compiling command: release
RMAN-03023: executing command: release
RMAN-08031: released channel: c1
RMAN>

(3) 继续在测试表中插入记录

SQL> insert into test values(2);
1 row inserted
SQL> commit;
Commit complete
SQL> select * from test;
                         A
---------------------------------------
                         1
                         2
SQL> alter system switch logfile;
System altered.
SQL>r
1* alter system switch logfile;
System altered.

(4) 关闭数据库,模拟丢失数据文件

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down

C:\>del D:\ORACLE\ORADATA\TEST\USER01.DBF

(5) 启动数据库,检查错误

SQL> startup
ORACLE instance started.
Total System Global Area  102020364 bytes
Fixed Size                    70924 bytes
Variable Size              85487616 bytes
Database Buffers           16384000 bytes
Redo Buffers                  77824 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 3 - see DBWR trace file
ORA-01110: data file 3: 'D:\ORACLE\ORADATA\TEST\USER01.DBF'

(6) 先打开数据库

SQL> alter database datafile 3 offline drop;
Database altered.
SQL> alter database open;
Database altered.

(7) 恢复该表空间
恢复脚本可以是恢复单个数据文件

run{
allocate channel c1 type disk;
restore datafile 3;
recover datafile 3;
sql 'alter database datafile 3 online';
release channel c1;
}

也可以是,恢复表空间

run{
allocate channel c1 type disk;
restore tablespace users;
recover tablespace users;
sql 'alter database datafile 3 online';
release channel c1;
}

过程如下:

C:\>rman
Recovery Manager: Release 8.1.6.0.0 - Production
RMAN> connect rcvcat rman/rman@back
RMAN-06008: connected to recovery catalog database
RMAN> connect target internal/virpure
RMAN-06005: connected to target database: TEST (DBID=1788174720)

RMAN> run{
2> allocate channel c1 type disk;
3> restore datafile 3;
4> recover datafile 3;
5> sql 'alter database datafile 3 online';
6> release channel c1;
7> }

RMAN-03022: compiling command: allocate
RMAN-03023: executing command: allocate
RMAN-08030: allocated channel: c1
RMAN-08500: channel c1: sid=13 devtype=DISK
RMAN-03022: compiling command: restore
RMAN-03022: compiling command: IRESTORE
RMAN-03023: executing command: IRESTORE
RMAN-08016: channel c1: starting datafile backupset restore
RMAN-08502: set_count=5 set_stamp=494177612 creation_time=16-MAY-03
RMAN-08089: channel c1: specifying datafile(s) to restore from backup set
RMAN-08523: restoring datafile 00003 to D:\ORACLE\ORADATA\TEST\USER01.DBF
RMAN-08023: channel c1: restored backup piece 1
RMAN-08511: piece handle=D:\BACKUP\TSUSER_05EN93AC_5_1 tag=TSUSER params=NULL
RMAN-08024: channel c1: restore complete
RMAN-03023: executing command: partial resync
RMAN-08003: starting partial resync of recovery catalog
RMAN-08005: partial resync complete
RMAN-03022: compiling command: recover
RMAN-03022: compiling command: recover(1)
RMAN-03022: compiling command: recover(2)
RMAN-03022: compiling command: recover(3)
RMAN-03023: executing command: recover(3)
RMAN-08054: starting media recovery
RMAN-03022: compiling command: recover(4)
RMAN-06050: archivelog thread 1 sequence 332 is already on disk as file D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00332.ARC
RMAN-06050: archivelog thread 1 sequence 333 is already on disk as file D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00333.ARC
RMAN-06050: archivelog thread 1 sequence 334 is already on disk as file D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00334.ARC
RMAN-03023: executing command: recover(4)
RMAN-08515: archivelog filename=D:\ORACLE\ORADATA\TEST\ARCHIVE\TESTT001S00332.ARC thread=1 sequence=332
RMAN-08055: media recovery complete
RMAN-03022: compiling command: sql
RMAN-06162: sql statement: alter database datafile 3 online
RMAN-03023: executing command: sql
RMAN-03022: compiling command: release
RMAN-03023: executing command: release
RMAN-08031: released channel: c1
RMAN>

(8) 检查数据是否完整

SQL> alter database open;
Database altered.

SQL> select * from test;
                         A
---------------------------------------
                         1
                         2

说明:
1、RMAN也可以实现单个表空间或数据文件的恢复,恢复过程可以在mount下或open方式下,如果在open方式下恢复,可以减少down机时间
2、如果损坏的是一个数据文件,建议offline并在open方式下恢复
3、这里可以看到,RMAN进行数据文件与表空间恢复的时候,代码都比较简单,而且能保证备份与恢复的可靠性,所以建议采用RMAN的备份与恢复

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