Oracle重建控制文件的实例教程

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前言

控制文件（control file）是一个相当小的文件（最多能增长到64M左右），其中包含Oracle需要的其他文件的一个目录。参数文件告知实例控制文件的位置，控制文件则告知示例数据库和在线重做日志文件的位置。控制文件还告知了Oracle其他一些事情，如已发生检查点的有关信息、数据库名（必须和db_name参数匹配）、创建数据库的时间戳、归档重做日志的历史（有时这会让控制文件变大）、RMAN信息等。

环境：OEL 5.7 + Oracle 10.2.0.5

背景：在Oracle的运维过程中，时常会遇到一些场景是需要重建控制文件才可以解决的。本文的场景可以通过复制控制文件到新路径，运行一段时间后，再用老的控制文件启动数据库重现。

1.当前故障现象

在使用旧的控制文件启动数据库时，报错ORA-01122、ORA-01110、ORA-01207:

SQL> shutdown abort
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 599785472 bytes
Fixed Size   2098112 bytes
Variable Size  218106944 bytes
Database Buffers  373293056 bytes
Redo Buffers  6287360 bytes
Database mounted.
ORA-01122: database file 1 failed verification check
ORA-01110: data file 1: '/oradata/cxywdb/system01.dbf'
ORA-01207: file is more recent than control file - old control file

2.分析故障原因

根据报错信息查找MOS文档:

ORA-1122, ORA-1110, ORA-1207 while open the database after crash (文档 ID 283927.1)

延伸思考一下，为什么会这样？

主要错误是ORA-01207，利用oerr工具看到Oralce对这个错误的详细描述是：

01207, 00000, "file is more recent than control file - old control file"
// *Cause: The control file change sequence number in the data file is
//         greater than the number in the control file. This implies that
//         the wrong control file is being used. Note that repeatedly causing
//         this error can make it stop happening without correcting the real
//         problem. Every attempt to open the database will advance the
//         control file change sequence number until it is great enough.
// *Action: Use the current control file or do backup control file recovery to
//         make the control file current. Be sure to follow all restrictions
//         on doing a backup control file recovery.

一般遇到这种情况，当前的控制文件肯定是找不到了。那么就得考虑重建控制文件来解决，MOS给出的建议也是重建控制文件。

3.重建控制文件

重建控制文件的核心步骤：

3.1 备份控制文件到trace

startup mount
alter database backup controlfile to trace;
oradebug setmypid
oradebug tracefile_name

3.2 启动数据库到nomount状态

shutdown abort
startup nomount;

3.3 确认重建控制文件的语句

vi control.sql
CREATE CONTROLFILE REUSE DATABASE "CXYWDB" NORESETLOGS FORCE LOGGING ARCHIVELOG
 MAXLOGFILES 16
 MAXLOGMEMBERS 3
 MAXDATAFILES 100
 MAXINSTANCES 8
 MAXLOGHISTORY 292
LOGFILE
 GROUP 5 '/oradata2/cxywdb/redo11.log' SIZE 50M,
 GROUP 6 '/oradata2/cxywdb/redo12.log' SIZE 50M,
 GROUP 7 '/oradata2/cxywdb/redo13.log' SIZE 50M
-- STANDBY LOGFILE
DATAFILE
 '/oradata/cxywdb/system01.dbf',
 '/oradata/cxywdb/undotbs01.dbf',
 '/oradata/cxywdb/sysaux01.dbf',
 '/oradata/cxywdb/users01.dbf',
 '/oradata/cxywdb/alfred01.dbf',
 '/oradata/cxywdb/alfred02.dbf',
 '/oradata/cxywdb/alfred03.dbf',
 '/oradata/cxywdb/alfred04.dbf',
 '/oradata/cxywdb/alfred05.dbf',
 '/oradata/cxywdb/dbs_i_alfred01.dbf'
CHARACTER SET ZHS16GBK
;

3.4 恢复并打开数据库

SQL> recover database;
Media recovery complete.
SQL> alter database open;
Database altered.

附：实际解决过程如下：

SQL> shutdown abort  
ORACLE instance shut down.
SQL> startup mount

ORACLE instance started.

Total System Global Area 599785472 bytes
Fixed Size     2098112 bytes
Variable Size    218106944 bytes
Database Buffers   373293056 bytes
Redo Buffers    6287360 bytes
Database mounted.
SQL> alter database backup controlfile to trace;

Database altered.

SQL> oradebug setmypid
Statement processed.
SQL> oradebug tracefile_name
/s01/oracle/admin/cxywdb/udump/cxywdb_ora_3983.trc
SQL> shutdown abort
ORACLE instance shut down.
SQL> startup nomount;
ORACLE instance started.

Total System Global Area 599785472 bytes
Fixed Size     2098112 bytes
Variable Size    218106944 bytes
Database Buffers   373293056 bytes
Redo Buffers    6287360 bytes
SQL> @control

Control file created.
SQL> select status from v$instance;

STATUS
------------
MOUNTED

SQL> recover database;
Media recovery complete.
SQL> alter database open;

Database altered.

总结

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