情况描述
客户报告数据库故障,新来的系统治理员误操作。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,须加以注重---------------------------------------------------- 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.注重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.由恢复治理器直接调用。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 这两个脚本中有具体的说明文档,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。
要害的内容有:
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.
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