ORA-600 2662

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标题：ORA-600 2662

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

在数据库恢复中,ORA-600 2662我想是很多人都非常熟悉的错误,下文是对于该错误的一些解释
ORA-600 2662解释说明

ERROR:
  Format: ORA-600 [2662] [a] [b] {c} [d] [e]
VERSIONS:
  versions 6.0 to 12.1
DESCRIPTION:
  A data block SCN is ahead of the current SCN.
  The ORA-600 [2662] occurs when an SCN is compared to the dependent SCN
  stored in a UGA variable.
  If the SCN is less than the dependent SCN then we signal the ORA-600 [2662]
  internal error.
ARGUMENTS:
  Arg [a]  Current SCN WRAP
  Arg [b]  Current SCN BASE
  Arg {c}  dependent SCN WRAP
  Arg [d]  dependent SCN BASE
  Arg [e]  Where present this is the DBA where the dependent SCN came from.

出现ORA-600 2662可能的原因

  (1) doing an open resetlogs with _ALLOW_RESETLOGS_CORRUPTION enabled
  (2) a hardware problem, like a faulty controller, resulting in a failed
      write to the control file or the redo logs
  (3) restoring parts of the database from backup and not doing the
      appropriate recovery
  (4) restoring a control file and not doing a RECOVER DATABASE USING BACKUP
      CONTROLFILE
  (5) having _DISABLE_LOGGING set during crash recovery
  (6) problems with the DLM in a parallel server environment
  (7) a bug

ORA-600 2662解决方法

   (1) if the SCNs in the error are very close, attempting a startup several
       times will bump up the dscn every time we open the database even if
       open fails. The database will open when dscn=scn.
   (2)You can bump the SCN either on open or while the database is open
      using Event:ADJUST_SCN
      Be aware that you should rebuild the database if you use this
      option.

_ALLOW_RESETLOGS_CORRUPTION

联系：手机/微信(+86 17813235971) QQ(107644445)

标题：_ALLOW_RESETLOGS_CORRUPTION

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

我相信_ALLOW_RESETLOGS_CORRUPTION 这个参数一定很多人都熟悉,是redo异常恢复的杀手锏之一,以下文章是来自官方的解释

DB_Parameter _ALLOW_RESETLOGS_CORRUPTION
========================================
This documentation has been prepared avoiding the mention of the complex
structures from the code and to simply give an insight to the 'damage it could
cause'.  The usage of this parameter leads to an in-consistent Database with no
other alternative but to rebuild the complete Database.  This parameter could
be used when we realize that there are no stardard options available and are
convinced that the customer understands the implications of using the Oracle's
secret parameter.  The factors to be considered are ;--
1. Customer does not have a good backup.
2. A lot of time and money has been invested after the last good backup and
   there is no possibility for reproduction of the lost data.
3. The customer has to be ready to export the full database and import it
   back after creating a new one.
4. There is no 100% guarantee that by using this parameter the database would
   come up.
5. Oracle does not support the database after using this parameter for
   recovery.
6. ALL OPTIONS including the ones mentioned in the action part of the error
   message have been tried.
By setting _ALLOW_RESETLOGS_CORRUPTION=TRUE, certain consistency checks are
SKIPPED during database open stage.  This basically means it does not check
the datafile headers as to what the status was before the shutdown and how it
was shutdown.  The following cases mention few of the checks that were skipped.
Case-I
------
Verification that the datafile present has not been restored from a BACKUP
taken before the database was opened successfully by using RESETLOGS.
ORA-01190: control file or data file %s is from before the last RESETLOGS
    Cause: Attempting to use a data file when the log reset information in
           the file does not match the control file.  Either the data file or
           the control file is a backup that was made before the most recent
           ALTER DATABASE OPEN RESETLOGS.
   Action: Restore file from a more recent backup.
Case-II
-------
Verification that the status bit of the datafile is not in a FUZZY state.
The datafile could be in this state due to the database going down when the
 - Datafile was on-line and open
 - Datafile was not closed cleanly (maybe due to OS).
ORA-01194: file %s needs more recovery to be consistent
    Cause: An incomplete recover session was started, but an insufficient
           number of logs were applied to make the file consistent.  The
           reported file was not closed cleanly when it was last opened by
           the database.  It must be recovered to a time when it was not
           being updated.  The most likely cause of this error is forgetting
           to restore the file from a backup before doing incomplete
           recovery.
   Action: Either apply more logs until the file is consistent or restore the
           file from an older backup and repeat recovery.
Case-III
--------
Verification that the COMPLETE recover strategies have been applied for
recovering the datafile and not any of the INCOMPLETE recovery options.
Basically because the complete recovery is one in which we even apply the
ON-LINE redo log files and open the DB without reseting the logs.
ORA-01113: file '%s' needs media recovery starting at log sequence # %s
    Cause: An attempt was made to open a database file that is in need of
           media recovery.
   Action: First apply media recovery to the file.
Case-IV
-------
Verification that the datafile has been recovered through an END BACKUP if the
control file indicates that it was in backup mode.
This is useful when the DB has crashed while in hot backup mode and we lost
all log files in DB version's less than V7.2.
ORA-01195: on-line backup of file %s needs more recovery to be consistent"
    Cause: An incomplete recovery session was started, but an insufficient
           number of logs were applied to make the file consistent.  The
           reported file is an on-line backup which must be recovered to the
           time the backup ended.
   Action: Either apply more logs until the file is consistent or resotre
          the database files from an older backup and repeat recovery.
In version 7.2, we could simply issue the ALTER DATABASE DATAFILE xxxx END
BACKUP statement and proceed with the recovery.  But again to issue this
statement, we need to have the ON-LINE redo logs or else we still are forced to
use this parameter.
Case-V
------
Verification that the data file status is not still in (0x10) MEDIA recovery
FUZZY.
When recovery is started, a flag is set in the datafile header status flag to
indicate that the file is presently in media recovery.  This is reset when
recovery is completed and at times when it has not been reset we are forced to
use this paramter.
ORA-01196: file %s is inconsistent due to a failed media recovery session
    Cause: The file was being recovered but the recovery did not terminate
           normally.  This left the file in an inconsistent state.  No more
           recovery was successfully completed on this file.
   Action: Either apply more logs until the file is consistent or restore the
           backup again and repeat recovery.
Case-VI
-------
Verification that the datafile has been restored form a proper backup to
correspond with the log files.  This situation could happen when we have
decided that the data file is invalid since its SCN is ahead of the last
applied logs SCN but it has not failed on one of the ABOVE CHECKS.
ORA-01152: file '%s' was not restored from a sufficientluy old backup"
    Cause: A manual recovery session was started, but an insufficient number
           of logs were applied to make the database consistent.  This file is
           still in the future of the last log applied.  Note that this
           mistake can not always be caught.
   Action: Either apply more logs until the database is consistent or
           restore the database file from an older backup and repeat
           recovery.

使用_ALLOW_RESETLOGS_CORRUPTION 参数需谨慎,因为该参数可能导致数据库逻辑不一致,甚至可能把本来很简单的一个恢复弄的非常复杂甚至不可恢复的后果,建议在oracle support支持下使用.另外使用该参数resetlogs库之后,强烈建议通过逻辑方式重建库

使用_allow_resetlogs_corruption导致ORA-00704/ORA-01555故障

联系：手机/微信(+86 17813235971) QQ(107644445)

标题：使用_allow_resetlogs_corruption导致ORA-00704/ORA-01555故障

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

以前写过一篇乱用_allow_resetlogs_corruption参数导致悲剧的文章,昨天晚上又遇到一个朋友不谨慎使用_allow_resetlogs_corruption导致ORA-00704/ORA-01555故障
环境描述
系统环境:solaris
数据库版本:10.2.0.5.7
数据存储方式:ASM
数据量:15T以上
补充事宜:数据库SCN距离headroom只有54天

报ORA-00020错误，实例crash
数据库因为超过了系统的进程数，出现dbwn进程写数据文件异常

Sun Aug 25 16:00:41 CST 2013
Errors in file /opt/oracle/admin/orcl/bdump/orcl_dbw0_7490.trc:
ORA-01148: 无法刷新数据文件 22 的文件大小
ORA-01110: 数据文件 22: '+DATA/orcl/datafile/index_jh.dbf'
ORA-00020: 超出最大进程数 ()
Sun Aug 25 16:00:41 CST 2013
Errors in file /opt/oracle/admin/orcl/bdump/orcl_dbw0_7490.trc:
ORA-01242: 数据文件出现介质故障: 数据库处于 NOARCHIVELOG 模式
ORA-01110: 数据文件 22: '+DATA/orcl/datafile/index_jh.dbf'
Sun Aug 25 16:00:41 CST 2013
DBW0: terminating instance due to error 1242
Termination issued to instance processes. Waiting for the processes to exit
Sun Aug 25 16:00:51 CST 2013
Instance termination failed to kill one or more processes
Instance terminated by DBW0, pid = 7490

ORA-00600[kcbtema_10]
实例恢复出现ORA-00600: 内部错误代码, 参数: [kcbtema_10], [1], [], [], [], [], [], []

Sun Aug 25 19:19:23 CST 2013
ALTER DATABASE OPEN
Sun Aug 25 19:19:38 CST 2013
Beginning crash recovery of 1 threads
 parallel recovery started with 16 processes
Sun Aug 25 19:19:40 CST 2013
Started redo scan
Sun Aug 25 19:20:07 CST 2013
Completed redo scan
 12016413 redo blocks read, 93405 data blocks need recovery
Sun Aug 25 19:20:19 CST 2013
Started redo application at
 Thread 1: logseq 53681, block 1091966
Sun Aug 25 19:20:19 CST 2013
Recovery of Online Redo Log: Thread 1 Group 1 Seq 53681 Reading mem 0
  Mem# 0: +DATA/orcl/onlinelog/redo_1_1.log
  Mem# 1: +DATA/orcl/onlinelog/redo_1_2.log
Sun Aug 25 19:20:21 CST 2013
Errors in file /opt/oracle/admin/orcl/bdump/orcl_p011_16944.trc:
ORA-00600: 内部错误代码, 参数: [kcbtema_10], [1], [], [], [], [], [], []
Sun Aug 25 19:20:23 CST 2013
Errors in file /opt/oracle/admin/orcl/bdump/orcl_p011_16944.trc:
ORA-00600: 内部错误代码, 参数: [kcbtema_10], [1], [], [], [], [], [], []
Sun Aug 25 19:20:23 CST 2013
Aborting crash recovery due to slave death, attempting serial crash recovery
Sun Aug 25 19:20:23 CST 2013
Beginning crash recovery of 1 threads
Sun Aug 25 19:20:23 CST 2013
Started redo scan
Sun Aug 25 19:20:47 CST 2013
Completed redo scan
 12016413 redo blocks read, 93405 data blocks need recovery
Sun Aug 25 19:20:54 CST 2013
Started redo application at
 Thread 1: logseq 53681, block 1091966
Sun Aug 25 19:20:54 CST 2013
Recovery of Online Redo Log: Thread 1 Group 1 Seq 53681 Reading mem 0
  Mem# 0: +DATA/orcl/onlinelog/redo_1_1.log
  Mem# 1: +DATA/orcl/onlinelog/redo_1_2.log
Sun Aug 25 19:20:54 CST 2013
Errors in file /opt/oracle/admin/orcl/udump/orcl_ora_16751.trc:
ORA-00600: 内部错误代码, 参数: [kcbtema_10], [1], [], [], [], [], [], []
Sun Aug 25 19:20:56 CST 2013
Aborting crash recovery due to error 600
Sun Aug 25 19:20:56 CST 2013
Errors in file /opt/oracle/admin/orcl/udump/orcl_ora_16751.trc:
ORA-00600: 内部错误代码, 参数: [kcbtema_10], [1], [], [], [], [], [], []
ORA-600 signalled during: ALTER DATABASE OPEN...

使用隐含参数

ALTER SYSTEM SET _allow_resetlogs_corruption=TRUE SCOPE=SPFILE;

报ORA-00704/ORA-01555
因为在前面的恢复中进行了不完全恢复，因此这里加入隐含参数，然后尝试resetlogs,然后报如下错误

Sun Aug 25 20:11:54 CST 2013
alter database open resetlogs
Sun Aug 25 20:12:10 CST 2013
RESETLOGS is being done without consistancy checks. This may result
in a corrupted database. The database should be recreated.
RESETLOGS after incomplete recovery UNTIL CHANGE 13429649847189
Resetting resetlogs activation ID 1312390734 (0x4e397e4e)
Sun Aug 25 20:16:25 CST 2013
Setting recovery target incarnation to 2
Sun Aug 25 20:16:42 CST 2013
************************************************************
Warning: The SCN headroom for this database is only 54 days!
************************************************************
Sun Aug 25 20:16:43 CST 2013
Assigning activation ID 1352200163 (0x5098efe3)
Thread 1 opened at log sequence 1
  Current log# 1 seq# 1 mem# 0: +DATA/orcl/onlinelog/redo_1_1.log
  Current log# 1 seq# 1 mem# 1: +DATA/orcl/onlinelog/redo_1_2.log
Successful open of redo thread 1
Sun Aug 25 20:16:43 CST 2013
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Sun Aug 25 20:16:52 CST 2013
SMON: enabling cache recovery
Sun Aug 25 20:16:52 CST 2013
ORA-01555 caused by SQL statement below (SQL ID: 4krwuz0ctqxdt, SCN: 0x0c36.d582339b):
Sun Aug 25 20:16:52 CST 2013
select ctime, mtime, stime from obj$ where obj# = :1
Sun Aug 25 20:16:52 CST 2013
Errors in file /opt/oracle/admin/orcl/udump/orcl_ora_2859.trc:
ORA-00704: 引导程序进程失败
ORA-00704: 引导程序进程失败
ORA-00604: 递归 SQL 级别 1 出现错误
ORA-01555: 快照过旧: 回退段号 143 (名称为 "_SYSSMU143$") 过小
Error 704 happened during db open, shutting down database
USER: terminating instance due to error 704
Termination issued to instance processes. Waiting for the processes to exit
Sun Aug 25 20:17:02 CST 2013
Instance termination failed to kill one or more processes
Instance terminated by USER, pid = 2859
ORA-1092 signalled during: alter database open resetlogs...

数据库当前SCN

SQL > select CHECKPOINT_CHANGE# from v$database;
CHECKPOINT_CHANGE#
------------------
    13429649947222
SQL > select distinct CHECKPOINT_CHANGE# from v$datafile_header;
CHECKPOINT_CHANGE#
------------------
    13429649947222

解决方法
因为该数据库版本为10.2.0.5.7,已经包含了scn patch,因此不能使用event或者隐含参数来修改scn,而且该库容量15T以上(asm),因此也无法使用bbed修改数据文件头,最后决定使用ordebug来解决该问题
使用oradebug DUMPvar SGA kcsgscn_
使用oradebug poke

sqlplus / as sysdba
startup mount
oradebug setmypid
oradebug DUMPvar SGA kcsgscn_
oradebug poke
recover database;
alter database open;

事后总结
查询MOS,发现ORA-00600[kcbtema_10] Raised During Recovery Operations (Doc ID 472282.1)

--故障原因
The cause of this problem has been identified and verified in unpublished Bug 5184359 ORA-600 [KCBTEMA_10].
Due to this bug, during recovery, the class designation of a data block has changed.
--处理方法
SQL>startup mount
SQL>recover database;
SQL>alter database open;

因为MOS上给的解决思路在该数据库中已经无法尝试，不能确定该方法一定可行，但是对于本次的恢复过程中，没有任何直接recover database操作(只有一次不完全恢复)确实让人有无限的遗憾和可惜。对于本次应该先查询MOS，尝试该种方法，慎重使用_allow_resetlogs_corruption参数

_allow_resetlogs_corruption和adjust_scn解决ORA-01190

联系：手机/微信(+86 17813235971) QQ(107644445)

标题：_allow_resetlogs_corruption和adjust_scn解决ORA-01190

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

一、模拟offline文件然后resetlogs操作

1.设置datafile 5数据文件offline
2.rman备份数据库
3.关闭原数据库，删除数据文件/当前日志和部分归档日志
4.执行不完全恢复，resetlogs打开数据库(如下面操作)
[oracle@xifenfei ora11g]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.3.0 Production on Thu Mar 15 07:36:59 2012
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> recover database until cancel;
ORA-00279: change 868870 generated at 03/15/2012 03:32:11 needed for thread 1
ORA-00289: suggestion :
/u01/oracle/oradata/archivelog/ora11g/1_29_777766629.dbf
ORA-00280: change 868870 for thread 1 is in sequence #29
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
SQL> alter database open resetlogs;
Database altered.
SQL> select file#,online_status,to_char(change#,'999999999999') from v$recover_file;
     FILE# ONLINE_STATUS  TO_CHAR(CHANGE#,'999999999
---------- -------------- --------------------------
         5 OFFLINE               868810
SQL> alter database datafile 5 online;
alter database datafile 5 online
*
ERROR at line 1:
ORA-01190: control file or data file 5 is from before the last RESETLOGS
ORA-01110: data file 5: '/u01/oracle/oradata/ora11g/xifenfei01.dbf'
SQL> select file#,to_char(checkpoint_change#,'999999999999'),
  2  to_char(last_change#,'999999999999') from v$datafile;
     FILE# TO_CHAR(CHECKPOINT_CHANGE# TO_CHAR(LAST_CHANGE#,'9999
---------- -------------------------- --------------------------
         1        868874
         2        868874
         3        868874
         4        868874
         5        868810                     868874
--可以看到offline的数据文件，没有因为resetlogs操作而改变
--CHECKPOINT_CHANGE#和RESETLOGS_CHANGE#信息
SQL> select file#,to_char(checkpoint_change#,'999999999999'),
  2  to_char(RESETLOGS_CHANGE#,'999999999999')
  3  from v$datafile_header;
     FILE# TO_CHAR(CHECKPOINT_CHANGE# TO_CHAR(RESETLOGS_CHANGE#,
---------- -------------------------- --------------------------
         1        868874                     868871
         2        868874                     868871
         3        868874                     868871
         4        868874                     868871
         5        868810                     787897

二、隐含参数设置

SQL> create pfile='/tmp/pfile' from spfile;
File created.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
在pfile中增加
_allow_resetlogs_corruption=true
_allow_error_simulation=TRUE(10g及其以上版本需要)

三、打开数据库,online离线文件

SQL> startup pfile='/tmp/pfile' mount;
ORACLE instance started.
Total System Global Area  368263168 bytes
Fixed Size                  1345016 bytes
Variable Size             293603848 bytes
Database Buffers           67108864 bytes
Redo Buffers                6205440 bytes
Database mounted.
--在mount状态下执行
SQL> alter session set events '10015 trace name adjust_scn level 2';
Session altered.
--[一定要]在mount状态下执行online操作
SQL> alter database datafile 5 online;
Database altered.
SQL> recover database until cancel;
ORA-00279: change 868810 generated at 03/13/2012 22:19:37 needed for thread 1
ORA-00289: suggestion :
/u01/oracle/oradata/archivelog/ora11g/1_27_777766629.dbf
ORA-00280: change 868810 for thread 1 is in sequence #27
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01190: control file or data file 1 is from before the last RESETLOGS
ORA-01110: data file 1: '/u01/oracle/oradata/ora11g/system01.dbf'
ORA-01112: media recovery not started
SQL> alter database open resetlogs;
Database altered.
SQL> select file#,online_status,to_char(change#,'999999999999') from v$recover_file;
no rows selected

姊妹篇:bbed解决ORA-01190

使用_allow_resetlogs_corruption打开无归档日志rman备份库

联系：手机/微信(+86 17813235971) QQ(107644445)

标题：使用_allow_resetlogs_corruption打开无归档日志rman备份库

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

rman还原恢复操作

--还原数据库
RMAN> restore database;
--恢复数据库
RMAN> recover database;
Starting recover at 2012-03-08 21:20:45
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=65 device type=DISK
starting media recovery
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of recover command at 03/08/2012 21:20:47
RMAN-06053: unable to perform media recovery because of missing log
RMAN-06025: no backup of archived log for thread 1 with sequence 2936 and starting SCN of 25991695 found to restore
RMAN-06025: no backup of archived log for thread 1 with sequence 2935 and starting SCN of 25991652 found to restore
RMAN-06025: no backup of archived log for thread 1 with sequence 2934 and starting SCN of 25991649 found to restore
……………………
RMAN-06025: no backup of archived log for thread 1 with sequence 2902 and starting SCN of 25991156 found to restore
这里报日志缺少，实际上是备份的数据库文件后，没有备份归档日志，归档日志全部丢失

进行不完全恢复

SQL> recover database until cancel;
ORA-00279: change 25991194 generated at 03/08/2012 20:33:58 needed for thread 1
ORA-00289: suggestion : /opt/oracle/oradata/archivelog/chf/1_2902_752334071.dbf
ORA-00280: change 25991194 for thread 1 is in sequence #2902
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/chf/system01.dbf'
ORA-01112: media recovery not started
SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/chf/system01.dbf'

查看相关SCN

SQL> select file#,to_char(checkpoint_change#,'999999999999') from v$datafile;
     FILE# TO_CHAR(CHECK
---------- -------------
         1      25992214
         2      25992214
         3      25992214
         4      25992214
         5      25992214
         6      25992214
         7      25992214
         8      25992214
         9      25992214
        10      25992214
        11      25992214
     FILE# TO_CHAR(CHECK
---------- -------------
        13      25992214
        14      25992214
13 rows selected.
SQL> select file#,online_status,to_char(change#,'999999999999') from v$recover_file;
     FILE# ONLINE_ TO_CHAR(CHANG
---------- ------- -------------
         1 ONLINE       25991194
         2 ONLINE       25991194
         3 ONLINE       25991194
         4 ONLINE       25991194
         5 ONLINE       25991194
         6 ONLINE       25991194
         7 ONLINE       25991194
         8 ONLINE       25991194
         9 ONLINE       25991194
        10 ONLINE       25991194
        11 ONLINE       25991194
     FILE# ONLINE_ TO_CHAR(CHANG
---------- ------- -------------
        13 ONLINE       25991194
        14 ONLINE       25991194
13 rows selected.
SQL> select file#,to_char(checkpoint_change#,'999999999999') from v$datafile_header;
     FILE# TO_CHAR(CHECK
---------- -------------
         1      25991194
         2      25991194
         3      25991194
         4      25991194
         5      25991194
         6      25991194
         7      25991194
         8      25991194
         9      25991194
        10      25991194
        11      25991194
     FILE# TO_CHAR(CHECK
---------- -------------
        13      25991194
        14      25991194
13 rows selected.
--发现数据文件scn和控制文件不一致，重建控制文件，然后查询相关scn
SQL> select file#,to_char(checkpoint_change#,'999999999999') from v$datafile;
     FILE# TO_CHAR(CHECK
---------- -------------
         1      25991194
         2      25991194
         3      25991194
         4      25991194
         5      25991194
         6      25991194
         7      25991194
         8      25991194
         9      25991194
        10      25991194
        11      25991194
     FILE# TO_CHAR(CHECK
---------- -------------
        13      25991194
        14      25991194
13 rows selected.
SQL> select file#,online_status,to_char(change#,'999999999999') from v$recover_file;
     FILE# ONLINE_ TO_CHAR(CHANG
---------- ------- -------------
         1 ONLINE       25991194
         2 ONLINE       25991194
         3 ONLINE       25991194
         4 ONLINE       25991194
         5 ONLINE       25991194
         6 ONLINE       25991194
         7 ONLINE       25991194
         8 ONLINE       25991194
         9 ONLINE       25991194
        10 ONLINE       25991194
        11 ONLINE       25991194
     FILE# ONLINE_ TO_CHAR(CHANG
---------- ------- -------------
        13 ONLINE       25991194
        14 ONLINE       25991194
13 rows selected.
SQL> select file#,to_char(checkpoint_change#,'999999999999') from v$datafile_header;
     FILE# TO_CHAR(CHECK
---------- -------------
         1      25991194
         2      25991194
         3      25991194
         4      25991194
         5      25991194
         6      25991194
         7      25991194
         8      25991194
         9      25991194
        10      25991194
        11      25991194
     FILE# TO_CHAR(CHECK
---------- -------------
        13      25991194
        14      25991194
13 rows selected.
--此时所有scn均一致

尝试打开数据库

SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/chf/system01.dbf'
SQL> recover database using backup controlfile until cancel;
ORA-00279: change 25991194 generated at 03/08/2012 20:33:58 needed for thread 1
ORA-00289: suggestion : /opt/oracle/oradata/archivelog/chf/1_2902_752334071.dbf
ORA-00280: change 25991194 for thread 1 is in sequence #2902
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/chf/system01.dbf'
ORA-01112: media recovery not started
SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/chf/system01.dbf'

使用隐含参数打开数据库

SQL> create pfile='/tmp/pfile' from spfile;
File created.
-------/tmp/pfile中加上----------
_allow_resetlogs_corruption= TRUE
---------------------------------
SQL> startup mount pfile='/tmp/pfile' force
ORACLE instance started.
Total System Global Area  622149632 bytes
Fixed Size                  2230912 bytes
Variable Size             419431808 bytes
Database Buffers          192937984 bytes
Redo Buffers                7548928 bytes
Database mounted.
SQL> alter database open resetlogs;
Database altered.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
READ WRITE

总结
这次的试验没有多少实际意义，但是可以说明几个问题：
1.所有的数据文件的scn都一致，甚至和控制文件的也一致，数据库不一定可以open成功
(怀疑是数据文件中的scn大于data header scn)
2.对于这样的问题，如果使用bbed修改所有数据文件header的scn不知道是否可以解决
3.如果rman只备份了数据文件而没有任何一个归档日志，数据库通过隐含参数还是可以open，抢救数据