情况描述

　　客户报告数据库故障，新来的系统管理员误操作。删掉了一些文件。

　　询问：删掉了那些文件？

　　答曰：所有重要数据文件，所有控制文件。数据库原来是归档模式，用rman备份数据，rman 使用控制文件。

　　幸运的是，最后一次rman full 备份是包括了控制文件在内。系统没有设定自动备份控制文件．现在状况是数据库无法启动．

　　不用说，客户的备份方案不够完善，但是这时候再去说这些话责备用户有事后诸葛亮之嫌，用户是上帝，不要去得罪他。还有，客户有Full备份（虽然不是自动备份控制文件，这样无法用常规的恢复步骤来进行恢复）。这对我们来说是个绝对的好消息。

　　下面我们通过一次模拟操作来演示这个问题的解决办法。

　　解决过程

　　首先，用控制文件作数据库系统的全备份：

　　代码:------------------------蓝色部分是输入内容，黑色部分是敏感信息，须加以注意----------------------------------------------------

　　C:WUTemp>rman target /

　　Recovery Manager: Release 9.2.0.1.0 - Production.

　　Copyright (c) 1995, 2002, Oracle Corporation. All rights reserved.

　　connected to target database: DEMO (DBID=3272375326)

　　RMAN> run {

　　2> allocate channel C1 type disk;

　　3> backup full tag 'FullBackup' format 'd:\KDE\%d_%u_%s_%p.dbf' database include current controlfile;

　　4> sql ' alter system archive log current';

　　5> release channel C1;

　　6> }

　　using target database controlfile instead of recovery catalog

　　allocated channel: C1

　　channel C1: sid=15 devtype=DISK

　　Starting backup at 18-JUL-04

　　channel C1: starting full datafile backupset

　　channel C1: specifying datafile(s) in backupset

　　including current SPFILE in backupset

　　including current controlfile in backupset

　　input datafile fno=00001 name=D:\ORACLE\ORADATA\DEMO\SYSTEM01.DBF

　　input datafile fno=00002 name=D:\ORACLE\ORADATA\DEMO\UNDOTBS01.DBF

　　input datafile fno=00004 name=D:\ORACLE\ORADATA\DEMO\EXAMPLE01.DBF

　　input datafile fno=00009 name=D:\ORACLE\ORADATA\DEMO\XDB01.DBF

　　input datafile fno=00005 name=D:\ORACLE\ORADATA\DEMO\INDX01.DBF

　　input datafile fno=00008 name=D:\ORACLE\ORADATA\DEMO\USERS01.DBF

　　input datafile fno=00003 name=D:\ORACLE\ORADATA\DEMO\DRSYS01.DBF

　　input datafile fno=00006 name=D:\ORACLE\ORADATA\DEMO\ODM01.DBF

　　input datafile fno=00007 name=D:\ORACLE\ORADATA\DEMO\TOOLS01.DBF

　　channel C1: starting piece 1 at 18-JUL-04

　　channel C1: finished piece 1 at 18-JUL-04

　　piece handle=D:\KDE\DEMO_01FR79OT_1_1.DBF comment=NONE

　　channel C1: backup set complete, elapsed time: 00:01:17

　　Finished backup at 18-JUL-04

　　sql statement: alter system archive log current

　　released channel: C1

　　--如上所示，我们做了一次数据库的Full备份．备份片中包括控制文件．注意上面输出内容的黑体部分．我们在后面的恢复操作中会用到．

　　模拟错误，关掉实例，删掉所有的控制文件和所有的.DBF文件。然后starup会看到如下的出错信息:

　　SQL> startup

　　ORACLE instance started.

　　Total System Global Area 152115804 bytes

　　Fixed Size 453212 bytes

　　Variable Size 100663296 bytes

　　Database Buffers 50331648 bytes

　　Redo Buffers 667648 bytes

　　ORA-00205: error in identifying controlfile, check alert log for more info

　　查看alert Log,应该是系统找不到控制文件．现在情形和客户问题一致．不过在继续讲述之前，我们还需要介绍一点背景知识．

　　背景知识：

　　在Oracle 816 以后的版本中,Oracle提供了一个包:DBMS_BACKUP_RESTORE.DBMS_BACKUP_RESTORE 包是由dbmsbkrs.sql 和 prvtbkrs.plb 这两个脚本创建的.catproc.sql 脚本运行后会调用这两个包.所以是每个数据库都有的这个包是Oracle服务器和操作系统之间IO操作的接口.由恢复管理器直接调用。而且据说这两个脚本的功能是内建到Oracle的一些库文件中的.

　　由此可见，我们可以在数据库 nomount 情况下调用这些package ,来达到我们的恢复目的。在dbmsbkrs.sql 和prvtbkrs.plb 这两个脚本中有详细的说明文档，出于篇幅问题，就不一一加以翻译了，但在下面会直接引用一些原文说明。

　　关键的内容有：

　　FUNCTION

　　deviceAllocate(

　　type IN varchar2 default NULL

　　,name IN varchar2 default NULL

　　,ident IN varchar2 default NULL

　　,noio IN boolean default FALSE

　　,params IN varchar2 default NULL )

　　RETURN varchar2;

　　-- Describe the device to be used for sequential I/O. For device types where

　　-- only one process at a time can use a device, this call allocates a device

　　-- for exclusive use by this session. The device remains allocated until

　　-- deviceDeallocate is called or session termination. The device can be used

　　-- both for creating and restoring backups.

　　--

　　-- Specifying a device allocates a context that exists until the session

　　-- terminates or deviceDeallocate is called. Only one device can be specified

　　-- at a time for a particular session. Thus deviceDeallocate must be called

　　-- before a different device can be specified. This is not a limitation since

　　-- a session can only read or write one backup at a time.

　　--

　　-- The other major effect of allocating a device is to specify the name space

　　-- for the backup handles (file names). The handle for a sequential file does

　　-- not necessarily define the type of device used to write the file. Thus it

　　-- is necessary to specify the device type in order to interpret the file

　　-- handle. The NULL device type is defined for all systems. It is the file

　　-- system supplied by the operating system. The sequential file handles are

　　-- thus normal file names.

　　--

　　-- A device can be specified either by name or by type.

　　-- If the type is specified but not the name, the system picks an

　　-- available device of that type.

　　-- If the name is specified but not the type, the type is determined

　　-- from the device.

　　-- If neither the type or the name is given, the backups are files in

　　-- the operating system file system.

　　-- Note that some types of devices, optical disks for example, can be shared

　　-- by many processes, and thus do not really require allocation of the device

　　-- itself. However we do need to allocate the context for accessing the

　　-- device, and we do need to know the device type for proper interpretation

　　-- of the file handle. Thus it is always necessary to make the device

　　-- allocation call before making most other calls in this package.

　　--

　　-- Input parameters:

　　-- type

　　-- If specified, this gives the type of device to use for sequential

　　-- I/O. The allowed types are port specific. For example a port may

　　-- support the type "TAPE" which is implemented via the Oracle tape

　　-- API. If no type is specified, it may be implied by specifying a

　　-- particular device name to allocate. The type should be allowed to

　　-- default to NULL if operating system files are to be used.

　　--

　　-- name

　　-- If specified, this names a particular piece of hardware to use for

　　-- accessing sequential files. If not specified, any available

　　-- device of the correct type will be allocated. If the device cannot

　　-- be shared, it is allocated to this session for exclusive use.

　　-- The name should be allowed to default to NULL if operating system

　　-- files are to be used.

　　--

　　-- ident

　　-- This is the users identifier that he uses to name this device. It

　　-- is only used to report the status of this session via

　　-- dbms_application_info. This value will be placed in the CLIENT_INFO

　　-- column of the V$SESSION table, in the row corresponding to the

　　-- session in which the device was allocated. This value can also

　　-- be queried with the dbms_application_info.read_client_info procedure.

　　--

　　-- noio

　　-- If TRUE, the device will not be used for doing any I/O. This allows

　　-- the specification of a device type for deleting sequential files

　　-- without actually allocating a piece of hardware. An allocation for

　　-- noio can also be used for issuing device commands. Note that some

　　-- commands may actually require a physical device and thus will get

　　-- an error if the allocate was done with noio set to TRUE.

　　--

　　-- params

　　-- This string is simply passed to the device allocate OSD. It is

　　-- completely port and device specific.

　　--

　　-- Returns:

　　-- It returns a valid device type. This is the type that should be

　　-- allocated to access the same sequential files at a later date. Note

　　-- that this might not be exactly the same value as the input string.

　　-- The allocate OSD may do some translation of the type passed in. The

　　-- return value is NULL when using operating system files.