RMAN备份与恢复之可脱机数据文件丢失
RMAN备份与恢复之可脱机数据文件丢失
一 表空间讲解
在上一篇文章(RMAN备份与恢复之控制文件丢失 ),我们讲解了控制文件丢失并且RMAN中有备份怎么处理,这篇文章讲解可脱机数据文件丢失的处理。
表空间是一种逻辑结构,表空间下可以存放数据文件。表空间有系统表空间(SYSTEM)、辅助表空间(SYSAUX)、用户表空间(USERS)、回退表空间(UNDOTBS1)、临时表空间(TEMP)、测试表空间(EXAMPLE)、数据表空间。其中系统表空间用于存储数据字典的信息,不能脱机,不能只读,也不能改名。辅助表空间用于存储一些工具以及一些常用的组件,10G开始引入,不能脱机,可以只读,可以改名。用户表空间用于存储用户数据的表空间,可以脱机,可以只读,可以改名。回退表空间用于存储DML操作的事务信息,不能脱机,不能只读,可以改名。临时表空间用于存放临时数据,不能脱机,不能只读,可以改名。数据表空间用于存放自定义数据,项目中我们一般创建数据表空间,数据存放在数据表空间,这是一种很好的做法,切忌把数据放在默认的USERS表空间。
至于有些表空间可以脱机,有些不可以。那是因为数据库在运行期间需要向这些表空间写入数据,比如系统表空间、辅助表空间、回退表空间、临时表空间,而用户表空间、测试表空间、数据表空间不同,只要没有对这些表空间进行操作,是可以脱机的。
二 备份与恢复可脱机数据文件讲解
备份与恢复可脱机数据文件,首先我们要使用RMAN做一个备份全库的操作,然后模拟USERS表空间丢失,此时我们查看数据会提示数据文件找不到。因为USERS表空间可以脱机,所以我们可以在SQL Plus中使USERS表空间离线,切记要先离线再进行下面的操作。因为在RMAN中我们有备份,所以我们可以在RMAN中对USERS表空间对应的数据文件编号进行还原,实际上后台就行进行了一个拷贝操作。还原成功后,我们需要对USERS表空间对应的数据文件编号进行恢复,等待恢复完成后,再在SQL Plus中使USERS表空间在线,所有的操作完成后,USERS表空间备份与恢复完成,我们可以对数据进行访问,测试是否恢复成功。需要注意的是,使表空间在线、离线、还原和恢复数据文件一些列的操作切记不要把编号弄错了,做这些操作应该确认USERS表空间的编号,默认是4号,但是由于后期的修改,USERS表空间数据文件的编号很不能不是4号。作为DBA,需要时刻保持谨慎!
三 模拟
Step1,RMAN中备份全库,并在SQL Plus确定数据的正确性
RMAN> BACKUP DATABASE;
Starting backup at 12-DEC-13
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00001 name=/u01/Oracle/oradata/justdb/system01.dbf
input datafile file number=00002 name=/u01/oracle/oradata/justdb/sysaux01.dbf
input datafile file number=00003 name=/u01/oracle/oradata/justdb/undotbs01.dbf
input datafile file number=00004 name=/u01/oracle/oradata/justdb/users01.dbf
channel ORA_DISK_1: starting piece 1 at 12-DEC-13
channel ORA_DISK_1: finished piece 1 at 12-DEC-13
piece handle=/u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_nnndf_TAG20131212T095816_9bl61rrn_.bkp tag=TAG20131212T095816 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:25
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 12-DEC-13
channel ORA_DISK_1: finished piece 1 at 12-DEC-13
piece handle=/u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_ncsnf_TAG20131212T095816_9bl62lw2_.bkp tag=TAG20131212T095816 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 12-DEC-13
[oracle@orcl backupset]$ ll 2013_12_12/
total 1025556
-rw------- 1 oracle oinstall 9830400 Dec 12 09:58 o1_mf_ncsnf_TAG20131212T095816_9bl62lw2_.bkp
-rw------- 1 oracle oinstall 1040334848 Dec 12 09:58 o1_mf_nnndf_TAG20131212T095816_9bl61rrn_.bkp
RMAN> LIST BACKUP;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
14 Full 992.13M DISK 00:00:19 12-DEC-13
BP Key: 14 Status: AVAILABLE Compressed: NO Tag: TAG20131212T095816
Piece Name: /u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_nnndf_TAG20131212T095816_9bl61rrn_.bkp
List of Datafiles in backup set 14
File LV Type Ckp SCN Ckp Time Name
---- -- ---- ---------- --------- ----
1 Full 1088247 12-DEC-13 /u01/oracle/oradata/justdb/system01.dbf
2 Full 1088247 12-DEC-13 /u01/oracle/oradata/justdb/sysaux01.dbf
3 Full 1088247 12-DEC-13 /u01/oracle/oradata/justdb/undotbs01.dbf
4 Full 1088247 12-DEC-13 /u01/oracle/oradata/justdb/users01.dbf
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
15 Full 9.36M DISK 00:00:01 12-DEC-13
BP Key: 15 Status: AVAILABLE Compressed: NO Tag: TAG20131212T095816
Piece Name: /u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_ncsnf_TAG20131212T095816_9bl62lw2_.bkp
SPFILE Included: Modification time: 12-DEC-13
SPFILE db_unique_name: JUSTDB
Control File Included: Ckp SCN: 1088267 Ckp time: 12-DEC-13
SQL> CONN SCOTT/tiger;
Connected.
SQL> SELECT * FROM tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
BONUS TABLE
DEPT TABLE
EMP TABLE
SALGRADE TABLE
Step2,SQL Plus中删除USERS表空间,模拟USERS表空间丢失
SQL> HO mv /u01/oracle/oradata/justdb/users01.dbf /opt/learn/
Step 3,scott用户查看数据失败
SQL> CONN SCOTT/tiger;
Connected.
SQL> DESC dept;
ERROR:
ORA-01116: error in opening database file 4
ORA-01110: data file 4: '/u01/oracle/oradata/justdb/users01.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Step4,SQL Plus中使第4号数据文件离线
SQL> CONN / AS SYSDBA;
Connected.
SQL> ALTER DATABASE DATAFILE 4 OFFLINE;
Database altered.
Step5,RMAN中还原4号数据文件
RMAN> RESTORE DATAFILE 4;
Starting restore at 12-DEC-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1 device type=DISK
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00004 to /u01/oracle/oradata/justdb/users01.dbf
channel ORA_DISK_1: reading from backup piece /u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_nnndf_TAG20131212T095816_9bl61rrn_.bkp
channel ORA_DISK_1: piece handle=/u01/oracle/fast_recovery_area/JUSTDB/backupset/2013_12_12/o1_mf_nnndf_TAG20131212T095816_9bl61rrn_.bkp tag=TAG20131212T095816
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
Finished restore at 12-DEC-13
Step6,RMAN中恢复4号文件
RMAN> RECOVER DATAFILE 4;
Starting recover at 12-DEC-13
using channel ORA_DISK_1
starting media recovery
media recovery complete, elapsed time: 00:00:00
Finished recover at 12-DEC-13
Step7,SQL Plus中使4号数据文件在线
SQL> ALTER DATABASE DATAFILE 4 ONLINE;
Database altered.
Step8,SQL Plus中查看数据
SQL> CONN SCOTT/tiger;
Connected.
SQL> DESC dept;
Name Null? Type
----------------------------------------- -------- ----------------------------
DEPTNO NOT NULL NUMBER(2)
DNAME VARCHAR2(14)
LOC VARCHAR2(13)
SQL> SELECT * FROM dept;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
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