一、什么是冷备份（offline backups）
数据库关闭时创建的备份就是冷备份，也叫做脱机备份。通俗点就是数据库处于不活动状态时创建的备份，就是冷备份。使用冷备份恢复时，数据库是正常关闭的，不需要进行修复操作，否则也需要使用归档日志与online redologs，才能将数据库修复到一个一致性状态。
二、进行一次冷备份并恢复
现在我们有测试环境bill数据库，现在处于正常运转状态。我们需要做的步骤。当然我们的所有实验都是建立在归档情况下的。
1、正常关闭数据库，shutdown immediate
2、cope数据文件到我们备份的目录
3、打开数据库
4、误操作删除数据文件
5、开始恢复，关闭数据库
6、拷贝备份文件到数据文件目录下
7、启动数据库
8、恢复数据库
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1、关闭数据库
[oracle@dap-test ~]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.3.0 Production on Fri Oct 25 13:19:18 2013
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
idle> conn / as sysdba;
    Connected.
    sys@DW> shutdown immediate;
    Database closed.
    Database dismounted.
    ORACLE instance shut down.
    sys@DW> exit
------------------------------------------------------------------------
2、进入oradata拷贝数据文件
[oracle@dap-test dw]$ pwd
    /data/oracle/u01/oradata/dw
    [oracle@dap-test dw]$ cp users01.dbf /data/oracle/u01/oradata/
[oracle@dap-test oradata]$ ll
    total 5.1M
    drwxr-x--- 2 oracle oinstall 4.0K Oct 18 11:55 dw
    -rw-r----- 1 oracle oinstall 5.1M Oct 25 13:23 users01.dbf
------------------------------------------------------------------------
3、打开数据库
[oracle@dap-test oradata]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.3.0 Production on Fri Oct 25 13:25:01 2013
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
idle> conn / as sysdba;
    Connected to an idle instance.
    idle> startup
    ORACLE instance started.
Total System Global Area 1620115456 bytes
    Fixed Size                  2228824 bytes
    Variable Size            1258294696 bytes
    Database Buffers          352321536 bytes
    Redo Buffers                7270400 bytes
    Database mounted.
    Database opened.
------------------------------------------------------------------------
4、误操作删除数据文件
[oracle@dap-test dw]$ rm -rf users01.dbf
------------------------------------------------------------------------
5、开始恢复，关闭数据库，提示找不到数据文件
sys@DW> shutdown immediate;
    ORA-01116: error in opening database file 4
    ORA-01110: data file 4: '/data/oracle/u01/oradata/dw/users01.dbf'
    ORA-27041: unable to open file
    Linux-x86_64 Error: 2: No such file or directory
    Additional information: 3
 
sys@DW> startup
    ORACLE instance started.
Total System Global Area 1620115456 bytes
    Fixed Size                  2228824 bytes
    Variable Size            1258294696 bytes
    Database Buffers          352321536 bytes
    Redo Buffers                7270400 bytes
    Database mounted.
    ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
    ORA-01110: data file 4: '/data/oracle/u01/oradata/dw/users01.dbf'
------------------------------------------------------------------------
6、拷贝备份文件到数据文件目录下
[oracle@dap-test dw]$ cp users01.dbf /data/oracle/u01/oradata/
------------------------------------------------------------------------
7、启动数据库
idle> conn / as sysdba;
    Connected to an idle instance.
    idle> startup
    ORACLE instance started.
Total System Global Area 1620115456 bytes
    Fixed Size                  2228824 bytes
    Variable Size            1258294696 bytes
    Database Buffers          352321536 bytes
    Redo Buffers                7270400 bytes
    Database mounted.
    ORA-01113: file 4 needs media recovery
    ORA-01110: data file 4: '/data/oracle/u01/oradata/dw/users01.dbf'
------------------------------------------------------------------------
8、恢复数据库
    idle> recover database
    Media recovery complete.