RMAN 备份,未使用catalog,控制文件丢失的解决办法

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。具体情况是：删掉了所有重要数据文件、所有控制文件。数据库原来是归档模式，用 RMAN (Recovery Manager) 备份数据，而 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。

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。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.

PROCEDURE restoreControlfileTo(cfname IN varchar2);

-- This copies the controlfile from the backup set to an operating system
-- file. If the database is mounted, the name must NOT match any of the
-- current controlfiles.
-- 从备份中恢复控制文件为操作系统文件．
-- 如果数据库在 mount 状态，控制文件名字则必须要匹配当前控制文件的名字
-- Input parameters:
-- cfname
-- Name of file to create or overwrite with the controlfile from the
-- backup set.

-- 备份集里的控制文件名字，创建或者覆盖控制文件．
PROCEDURE restoreDataFileTo( dfnumber IN binary_integer
,toname IN varchar2 default NULL);
--
-- restoreDataFileTo creates the output file from a complete backup in the
-- backup set.
-- 从完整的备份集里创建输出文件

如果您有兴趣可以去阅读一下这两个文件的注释说明．

解决过程

首先，用控制文件作数据库系统的全备份：

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．

我们首先尝试恢复控制文件：

SQL>startup force nomount;

SQL> DECLARE
2 devtype varchar2(256);
3 done boolean;
4 BEGIN
5 devtype:=sys.dbms_backup_restore.deviceAllocate(type=>'',ident=>'T1');
6 sys.dbms_backup_restore.restoreSetDatafile;
7 sys.dbms_backup_restore.restoreControlfileTo (cfname=>'d:\oracle\Control01.ctl');
8 sys.dbms_backup_restore.restoreBackupPiece(done=>done,handle=>'D:\KDE\DEMO_01FR79OT_1_1.DBF', params=>null);
9 sys.dbms_backup_restore.deviceDeallocate;
10 END;
11 /

PL/SQL procedure successfully completed.

OK,控制文件恢复完成．对以上内容的解释:

• 第五行 分配一个device channel，因为使用的操作系统文件，所以这里为空，如果是从磁带上恢复要用 “sbt_tape”；
• 第六行 指明开始restore ；
• 第七行 指出待恢复文件目标存储位置；
• 第八行 从哪个备份片中恢复；
• 第九行 释放设备通道．

不妨对以上操作的结果验证一下：

SQL> host dir d:\oracle
Volume in drive D is DATA
Volume Serial Number is DC79-57F8
Directory of d:\oracle

07/18/2004 09:08 PM <DIR> .
07/18/2004 09:08 PM <DIR> ..
06/08/2004 03:21 PM <DIR> admin
07/18/2004 09:08 PM 1,871,872 CONTROL01.CTL
07/16/2004 11:27 AM <DIR> ORA92
07/18/2004 09:02 PM <DIR> oradata

这样，我们成功的 restore 了控制文件 .如果控制文件在 Full 备份之后单独做的，接下来关掉实例，拷贝控制文件到具体位置，然后 rman 执行 restore database; 即可。
可是，我们这里的情况有些不同．
视丢失文件的情况而定，继续进行如下的恢复操作：

SQL> DECLARE
2 devtype varchar2(256);
3 done boolean;
4 BEGIN
5 devtype:=sys.dbms_backup_restore.deviceAllocate (type=>'',ident=>'t1');
6 sys.dbms_backup_restore.restoreSetDatafile;
7 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>01,toname=>'d:\oracle\oradata\demo\SYSTEM01.DBF');
8 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>02,toname=>'d:\oracle\oradata\demo\UNDOTBS01.DBF');
9 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>03,toname=>'d:\oracle\oradata\demo\DRSYS01.DBF');
10 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>04,toname=>'d:\oracle\oradata\demo\EXAMPLE01.DBF');
11 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>05,toname=>'d:\oracle\oradata\demo\INDX01.DBF');
12 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>06,toname=>'d:\oracle\oradata\demo\ODM01.DBF');
13 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>07,toname=>'d:\oracle\oradata\demo\TOOLS01.DBF');
14 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>08,toname=>'d:\oracle\oradata\demo\USERS01.DBF');
15 sys.dbms_backup_restore.restoreDatafileTo(dfnumber=>09,toname=>'d:\oracle\oradata\demo\XDB01.DBF');
16 sys.dbms_backup_restore.restoreBackupPiece(done=>done,handle=>'D:\KDE\DEMO_01FR79OT_1_1.DBF',
params=>null);
17 sys.dbms_backup_restore.deviceDeallocate;
18 END;
19 /

PL/SQL procedure successfully completed.

–我们的情形是所有的数据文件都丢失了，那就如法炮制 ………..
–文件对应编号来自前面全备份时候的屏幕输出内容．所以，在备份的时候保留操作 Log 是个很好的习惯．

SQL> startup force mount;
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
Database mounted.
SQL> Recover database using backup controlfile until cancel ;
ORA-00279: change 243854 generated at 07/18/2004 20:57:03 needed for thread 1
ORA-00289: suggestion : D:\KDE\ARC00002.001
ORA-00280: change 243854 for thread 1 is in sequence #2
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

D:\KDE\ARC00002.001
ORA-00279: change 244089 generated at 07/18/2004 20:58:18 needed for thread 1
ORA-00289: suggestion : D:\KDE\ARC00003.001
ORA-00280: change 244089 for thread 1 is in sequence #3
ORA-00278: log file 'D:\KDE\ARC00002.001' no longer needed for this recovery

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
CANCEL
Media recovery cancelled.

SQL> alter database open resetlogs;
Database altered.

最后，不得不resetlogs ．

然后，打扫战场，马上进行数据库的全备份。如果您是DBA的话，应该进一步制定并完善备份计划．亡羊补牢，为时未晚。

总结一下

• 控制文件在备份中意义重大，建议每次对其单独备份，如果数据库版本允许的话，应该设置为控制文件自动备 份。同时应该尽可能地增大CONTROL_FILE_RECORD_KEEP_TIME这个初始化参数的值。以便备份信息能更长时间的保留
• 应该制定比较完善的备份计划，否则备份计划一旦出现缺口，将可能给系统带来灾难．记住， ＂可能出错的地方一定会出错＂．
• 熟悉RMAN内部备份机制，对DBMS_BACKUP_RESTORE的用法有一定的掌握在关键时侯很有帮助．
• 备份脚本应该对Log重定向并保存．以便在出错的查找有用信息．

参考信息

RMAN Recovery Without Recovery Catalog or Controlfiles by Bonnie Bizzaro
dbmsbkrs.sql 和 prvtbkrs.plb 文件说明注释(可在你的系统 $ORACLE_HOME/rdbms/admin/中找到．)

相关链接

本文的更多信息，请看ITpub 论坛对此话题的讨论 – http://www.itpub.net/244345.html
本文的Blog讨论，请看CSDN 对此话题的讨论 – http://blog.csdn.net/fenng/archive/2004/07/19/44945.aspx

本文是对旧文章的整理．请看这篇文章的旧版本
RMAN, RMAN备份, RMAN恢复, 恢复