Oracle数据文件物理删除后的恢复
做系统管理的都是这样，难免会误删文件，某天要是把某个Oracle数据文件删除，那该如何恢复呢？(这里数据库是OPEN的，并且未关闭)
建立测试表空间
创建测试用户
插入测试数据
删除数据文件
恢复数据库文件
建立测试表空间

SQL> select name from v$datafile;
NAME
--------------------------------------------------------------------------------
/opt/oracle/oradata/member/system01.dbf
/opt/oracle/oradata/member/sysaux01.dbf
/opt/oracle/oradata/member/undotbs01.dbf
/opt/oracle/oradata/member/users01.dbf

SQL> create tablespace test datafile '/opt/oracle/oradata/member/test01.dbf' size 10m;
Tablespace created.

SQL> select name from v$datafile;
NAME
--------------------------------------------------------------------------------
/opt/oracle/oradata/member/system01.dbf
/opt/oracle/oradata/member/sysaux01.dbf
/opt/oracle/oradata/member/undotbs01.dbf
/opt/oracle/oradata/member/users01.dbf
/opt/oracle/oradata/member/test01.dbf

2.创建测试账户
SQL> create user test identified by test default tablespace test;
SQL> grant connect,resource to test;

3.插入测试数据
SQL> conn test/test
SQL> create table t1(id int);
SQL> insert into t1 values(1);
SQL> select * from t1;
ID
----------
1

4.删除数据文件
[oracle@db2 ~]$ rm -f /opt/oracle/oradata/member/test01.dbf
[oracle@db2 ~]$ sqlplus test/test
SQL> create table t2 as select * from t1;
create table t2 as select * from t1
*
ERROR at line 1:
ORA-01116: error in opening database file 5
ORA-01110: data file 5: '/opt/oracle/oradata/member/test01.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

SQL> select table_name,tablespace_name from user_tables;
TABLE_NAME TABLESPACE_NAME
------------------------------ ------------------------------
T1 TEST
数据文件被删除了，这怎么办呢？这个时候千万别重启数据库，否则数据就丢失了

5.数据文件恢复
[oracle@db2 ~]$ ps -ef |grep dbw0
oracle 3309 1 0 12:07 ? 00:00:00 ora_dbw0_member
oracle 6217 5105 0 15:29 pts/0 00:00:00 grep dbw0
#找到ora_dbw0_SID的进程号3309

[oracle@db2 ~]$ cd /proc/3309/fd
#以上3309就是进程号，然后执行ls -al查看文件的链接

可以看到文件27就是被删除的文件
[oracle@db2 fd]$ cp 27 /opt/oracle/oradata/member/test01.dbf

查看test表空间状态
SQL> select name,status from v$datafile;
NAME STATUS
---------------------------------------- -------
/opt/oracle/oradata/member/system01.dbf SYSTEM
/opt/oracle/oradata/member/sysaux01.dbf ONLINE
/opt/oracle/oradata/member/undotbs01.dbf ONLINE
/opt/oracle/oradata/member/users01.dbf ONLINE
/opt/oracle/oradata/member/test01.dbf ONLINE

下线test01表文件
SQL> alter database datafile '/opt/oracle/oradata/member/test01.dbf' offline;
SQL> recover datafile '/opt/oracle/oradata/member/test01.dbf';
Media recovery complete.

SQL> alter database datafile '/opt/oracle/oradata/member/test01.dbf' online;
Database altered.

#以上就成功恢复了，若是出现
SQL> recover datafile '/opt/oracle/oradata/member/test01.dbf';
ORA-00283: recovery session canceled due to errors
ORA-01110: data file 5: '/opt/oracle/oradata/member/test01.dbf'
ORA-01157: cannot identify/lock data file 5 - see DBWR trace file
ORA-01110: data file 5: '/opt/oracle/oradata/member/test01.dbf'
则有可能是/opt/oracle/oradata/member/test01.dbf文件的权限问题引起，在root用户下

[root@db2 ~]# chown -R oracle.oinstall /opt/oracle/oradata/member/test01.dbf
再recover datafile '/opt/oracle/oradata/member/test01.dbf'

实验完成后，删除测试用户及测试表空间
SQL> drop user test cascade;
SQL> drop tablespace test INCLUDING CONTENTS AND DATAFILES;