转自：http://www.ixdba.net/article/34/272$1.html

数据库从mount到open的过程，是个详细的检查过程，oracle在open过程中会进行很多的检测，数据文件的存在，以及scn一致性等等，其中非常重要的并且大家熟知的有下面两个信息检测：

1：第一次检查数据文件头的检查点计数（chenkpoint cnt）是否和控制文件中的检查点计数（chenkpoint cnt）一致，此步骤主要是用以确认数据文件是否来自同一版本。

2：第二次检查数据文件头的开始scn（checkpoint scn）和控制文件中记录的每个文件的结束scn（stop scn）是否一致，如果两者相同，不需要进行恢复，如果不同，则数据库需要进行恢复。

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以上两个检测，总结起来，第一次是版本一致性检测，第二次是是否需要恢复性的检测。

下面通过具体的操作，来演示上面两个过程的具体实现。

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 17:17:16 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to:

Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL>quit

Disconnected from Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

[oracle@www cicro]$ ls

cicrodb.dbf      control03.ctl  example01.dbf  redo02.log    test           undotbstemp.dbf cicrodb.dbf.bak  cwmlite01.dbf  indx01.dbf     redo03.log    tools01.dbf    users01.dbf  control01.ctl    cws33db.dbf    odm01.dbf      system01.dbf  undotbs01.dbf  xdb01.dbf control02.ctl    drsys01.dbf    redo01.log     temp01.dbf    undotbs02.dbf

[oracle@www cicro]$ cp cicrodb.dbf cicrodb.dbf.old

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 15:36:32 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to an idle instance.

SQL> startup mount

ORACLE instance started.

Total System Global Area  235999352 bytes

Fixed Size                   450680 bytes

Variable Size             201326592 bytes

Database Buffers           33554432 bytes

Redo Buffers                 667648 bytes

Database mounted.

SQL> alter session set events 'immediate trace name file_hdrs level 10';

Session altered.

 

此时，/opt/oracle/oradata/cicro/cicrodb.dbf数据文件头信息如下：

 

**********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:137 scn: 0x0800.0195c4d2 08/10/2006 15:36:04

 Stop scn: 0x0800.0195c4d2 08/10/2006 15:36:04

 

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 

以上是控制文件的信息，也就是说信息是从控制文件得到的。

 

以下信息是读取数据文件头得到的。

 

 aux_file is NOT DEFINED

 FILE HEADER:

        Software vsn=153092096=0x9200000, Compatibility Vsn=134217728=0x8000000

        Db ID=44014079=0x29f99ff, Db Name='CICRO'

        Activation ID=0=0x0

        Control Seq=1295=0x50f, File size=7680=0x1e00

        File Number=11, Blksiz=8192, File Type=3 DATA

Tablespace #12 - CICRO  rel_fn:11

Creation   at   scn: 0x0000.01213333 12/28/2005 15:28:58

Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0

 reset logs count:0x239b4610 scn: 0x0800.017b0530 recovered at 08/10/2006 15:18:39

 status:0x0 root dba:0x00000000 chkpt cnt: 137 ctl cnt:136

begin-hot-backup file size: 0

Checkpointed at scn:  0x0800.0195c4d2 08/10/2006 15:36:04

 thread:1 rba:(0x1a.2ac.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

Backup Checkpointed at scn:  0x0000.00000000

 thread:0 rba:(0x0.0.0)

 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

External cache id: 0x0 0x0 0x0 0x0

Absolute fuzzy scn: 0x0000.00000000

Recovery fuzzy scn: 0x0000.00000000 08/10/2006 14:18:35

Terminal Recovery Stamp scn: 0x0000.00000000 01/01/1988 00:00:00

 

从以上可以看出，此时数据库数据文件头Checkpoint cnt和控制文件Checkpoint cnt相同。数据文件头的Checkpointed at scn和控制文件中的Checkpointed at scn也相同。

 

然后在dump出控制文件信息，如下

 

SQL> alter session set events 'immediate trace name CONTROLF level 10';

Session altered.

 

也同理找出/opt/oracle/oradata/cicro/cicrodb.dbf文件在控制文件中记录的信息。

 

***********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:137 scn: 0x0800.0195c4d2 08/10/2006 15:36:04

 Stop scn: 0x0800.0195c4d2 08/10/2006 15:36:04

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

 

以上可以看到，在正常情况下，控制文件中dump出来的数据文件的scn，和dump数据文件头得到的数据文件scn是一样的，在dump数据文件头得到的信息中，一部分来自与控制文件，一部分来自与数据文件头，

如上说明。

 

继续往下测试：

 

SQL> alter database open;

Database altered.

SQL> quit

Disconnected from Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 15:54:11 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to:

Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

SQL> alter system switch logfile;

System altered.

SQL> /

 

System altered.

 

执行日志切换，然后触发完全检查点，这样checkpoint  scn将被更新。

 

SQL> select * from v$log;

 

 GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS

---------- ---------- ---------- ---------- ---------- --- ----------------

FIRST_CHANGE# FIRST_TIM

------------- ---------

         1          1         26  104857600          1 YES INACTIVE

   8.7961E+12 10-AUG-06

 

         2          1         27  104857600          1 YES INACTIVE

   8.7961E+12 10-AUG-06

 

         3          1         28  104857600          1 NO  CURRENT

   8.7961E+12 10-AUG-06

 

然后关闭数据库

 

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> quit

Disconnected from Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 – Production

 

接下来把原来备份的cicrodb.dbf替换过来。

 

[oracle@www cicro]$ ls

cicrodb.dbf      control02.ctl  drsys01.dbf    redo01.log    temp01.dbf     undotbs02.dbf cicrodb.dbf.bak  control03.ctl  example01.dbf  redo02.log  test       undotbstemp.dbf cicrodb.dbf.old  cwmlite01.dbf  indx01.dbf     redo03.log    tools01.dbf    users01.dbf control01.ctl    cws33db.dbf    odm01.dbf      system01.dbf  undotbs01.dbf  xdb01.dbf

[oracle@www cicro]$ mv cicrodb.dbf cicrodb.dbf.new

[oracle@www cicro]$ mv cicrodb.dbf.old  cicrodb.dbf

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 15:57:36 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to an idle instance.

 

SQL> startup mount

ORACLE instance started.

Total System Global Area  235999352 bytes

Fixed Size                   450680 bytes

Variable Size             201326592 bytes

Database Buffers           33554432 bytes

Redo Buffers                 667648 bytes

Database mounted.

SQL> alter session set events 'immediate trace name CONTROLF level 10';

Sessionaltered.

 

以下是dump出来的控制文件中cicrodb.dbf文件的信息。

 

***********************************************************

DATABASE ENTRY

*********************************************************** (blkno = 0x1, size = 192, max = 1, in-use = 1, last-recid= 0)

 DF Version: creation=0x9200000 compatible=0x8000000, Date  09/14/2005 14:01:35

 DB Name "CICRO"

 Database flags = 0x00404001

 Controlfile Creation Timestamp  09/14/2005 14:01:35

 Incmplt recovery scn: 0x0000.00000000

 Resetlogs scn: 0x0800.017b0530 Resetlogs Timestamp  08/02/2006 02:29:36

 Prior resetlogs scn: 0x0000.0123d11d Prior resetlogs Timestamp  12/29/2005 11:52:32

 Redo Version: creation=0x9200000 compatable=0x9200000

 #Data files = 14, #Online files = 14

 Database checkpoint: Thread=1 scn: 0x0800.0195c773

 Threads: #Enabled=1, #Open=0, Head=0, Tail=0

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

 Max log members = 5, Max data members = 1

 Arch list: Head=3, Tail=3, Force scn: 0x0800.0195c20fscn: 0x0800.0195c761

 Controlfile Checkpointed at scn:  0x0800.0195c761 08/10/2006 15:56:27

 thread:0 rba:(0x0.0.0)

 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

 

 

 

***********************************************************

CHECKPOINT PROGRESS RECORDS

***********************************************************

 (blkno = 0x4, size = 104, max = 1, in-use = 1, last-recid= 0)

THREAD #1 - status:0x1 flags:0x0 dirty:0

low cache rba:(0xffffffff.ffffffff.ffff) on disk rba:(0x1c.2.0)

on disk scn: 0x0800.0195c761 08/10/2006 15:56:27

resetlogs scn: 0x0800.017b0530 08/02/2006 02:29:36

heartbeat: 598125514 mount id: 73105079

MTTR statistics status: 0

 

 

***********************************************************

DATA FILE RECORDS

***********************************************************DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:140 scn: 0x0800.0195c773 08/10/2006 15:57:01

 Stop scn: 0x0800.0195c773 08/10/2006 15:57:01

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

然后在dump出数据文件头信息

 

SQL> alter session set events 'immediate trace name file_hdrs level 10';

 

Session altered.

 

***********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:140 scn: 0x0800.0195c773 08/10/2006 15:57:01

 Stop scn: 0x0800.0195c773 08/10/2006 15:57:01

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

以上信息是来自与控制文件，所以与控制文件信息相同。

 

以下信息是来自于当前的数据文件头，此时由于cicrodb.dbf是旧的数据文件，就出现问题了。

 FILE HEADER:

        Software vsn=153092096=0x9200000, Compatibility Vsn=134217728=0x8000000

        Db ID=44014079=0x29f99ff, Db Name='CICRO'

        Activation ID=0=0x0

        Control Seq=1295=0x50f, File size=7680=0x1e00

        File Number=11, Blksiz=8192, File Type=3 DATA

Tablespace #12 - CICRO  rel_fn:11

Creation   at   scn: 0x0000.01213333 12/28/2005 15:28:58

Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0

 reset logs count:0x239b4610 scn: 0x0800.017b0530 recovered at 08/10/2006 15:18:39

 status:0x0 root dba:0x00000000 chkpt cnt: 137 ctl cnt:136 

（chkpt cnt: 137是记录checkpoint的执行次数，由于是旧的数据文件，chkpt cnt的值还是原来没有替换cicrodb.dbf以前的状态，所以与dump出来的控制文件中记录的chkpt cnt就出现了不同，此时检测就不能通过。）

begin-hot-backup file size: 0

Checkpointed at scn:  0x0800.0195c4d2 08/10/2006 15:36:04

（此时文件的Checkpointed at scn是在没有替换cicrodb.dbf以前的Checkpointed at scn，与dump出来的控制文件中记录的Checkpointed at scn不相同，因此，open时肯定需要恢复）

 thread:1 rba:(0x1a.2ac.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

Backup Checkpointed at scn:  0x0000.00000000

 thread:0 rba:(0x0.0.0)

 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000  00000000 00000000

External cache id: 0x0 0x0 0x0 0x0

Absolute fuzzy scn: 0x0000.00000000

Recovery fuzzy scn: 0x0000.00000000 08/10/2006 14:18:35

Terminal Recovery Stamp scn: 0x0000.00000000 01/01/1988 00:00:00

 

尝试删除cicrodb.dbf文件，然后dump出来数据文件头信息，看看又是什么情况

 

SQL> quit

Disconnected from Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

[oracle@www cicro]$ ls

cicrodb.dbf      control02.ctl  drsys01.dbf    redo01.log    temp01.dbf     undotbs02.dbf cicrodb.dbf.bak  control03.ctl  example01.dbf redo02.log    test      undotbstemp.dbf cicrodb.dbf.new  cwmlite01.dbf  indx01.dbf     redo03.log    tools01.dbf    users01.dbf control01.ctl    cws33db.dbf    odm01.dbf      system01.dbf  undotbs01.dbf  xdb01.dbf

[oracle@www cicro]$ mv cicrodb.dbf  cicrodb.dbf.nn

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 16:25:13 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to:

Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 – Production

 

SQL> alter session set events 'immediate trace name file_hdrs level 10';

Session altered.

SQL>

 

此时Dump出数据文件头信息，如下：

 

***********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:140 scn: 0x0800.0195c773 08/10/2006 15:57:01

 Stop scn: 0x0800.0195c773 08/10/2006 15:57:01

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000

  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

以上仍就是转自控制文件的信息。

 

ORA-01157: cannot identify/lock data file 11 - see DBWR trace file

ORA-01110: data file 11: '/opt/oracle/oradata/cicro/cicrodb.dbf'

*** Error 1157 in open/read file # 11 ***

 

此时就提示ORA-01157错误，也就是数据库open时要报的错误。

 

继续下面的测试，恢复刚才删除的数据文件，尝试打开数据库：

 

SQL> quit

Disconnected from Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

[oracle@www cicro]$ ls

cicrodb.dbf.bak  control02.ctl  drsys01.dbf    redo01.log    temp01.dbf     undotbs02.dbf cicrodb.dbf.new  control03.ctl  example01.dbf  redo02.log  test        undotbstemp.dbf cicrodb.dbf.nn   cwmlite01.dbf  indx01.dbf     redo03.log    tools01.dbf    users01.dbf control01.ctl    cws33db.dbf    odm01.dbf      system01.dbf  undotbs01.dbf  xdb01.dbf

[oracle@www cicro]$ mv cicrodb.dbf.nn  cicrodb.dbf

[oracle@www cicro]$ sqlplus "/as sysdba"

SQL*Plus: Release 9.2.0.1.0 - Production on Thu Aug 10 16:35:06 2006

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to:

Oracle9i Release 9.2.0.1.0 - Production

JServer Release 9.2.0.1.0 - Production

SQL> alter database open;

alter database open

*

ERROR at line 1:

ORA-01113: file 11 needs media recovery

ORA-01110: data file 11: '/opt/oracle/oradata/cicro/cicrodb.dbf'

 

出现需要恢复的提示，出现这个问题的原因就是上面所述。

 

执行恢复操作：

 

SQL> recover database;

IXDBA.NET社区论坛

Media recovery complete。

 

SQL> alter session set events 'immediate trace name file_hdrs level 10';

Session altered.

 

此时dump出cicrodb.dbf文件的数据文件头，信息如下：

 

***********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:141 scn: 0x0800.0195c773 08/10/2006 15:57:01

 Stop scn: 0x0800.0195c771 08/10/2006 15:57:01

（经过恢复，控制文件中的Stop scn:有原来的Stop scn: 0x0800.0195c773改变为现在的Stop scn: 0x0800.0195c771）

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

FILE HEADER:

        Software vsn=153092096=0x9200000, Compatibility Vsn=134217728=0x8000000

        Db ID=44014079=0x29f99ff, Db Name='CICRO'

        Activation ID=0=0x0

        Control Seq=1311=0x51f, File size=7680=0x1e00

        File Number=11, Blksiz=8192, File Type=3 DATA

Tablespace #12 - CICRO  rel_fn:11

Creation   at   scn: 0x0000.01213333 12/28/2005 15:28:58

Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0

 reset logs count:0x239b4610 scn: 0x0800.017b0530 recovered at 08/10/2006 16:38:28

 status:0x0 root dba:0x00000000 chkpt cnt: 141 ctl cnt:140

（此时数据文件头的chkpt cnt: 141与控制文件的chkpt cnt相同）

 

为什么数据文件头记录的ctl cnt:140 比控制文件中小1呢?
是这样的:
当检查点更新控制文件和数据文件头上的chkpt cnt信息时
在更新控制文件之前，可以获得当前的ctl cnt（也就是控制文件中的cnt），这个信息被记入了数据文件，也就是 ctl cnt:140
为什么要写这个到数据文件呢?
因为不能保证当前更新控制文件上的 checkpoint cnt一定会成功（数据库可能突然crash掉了），记录之前成功的ctl cnt可以确保上一次的checkpoint是成功完成的，从而省略了校验步骤。

 

begin-hot-backup file size: 0

Checkpointed at scn:  0x0800.0195c771 08/10/2006 15:57:01

（此时数据文件头的Checkpointed at scn也和控制文件中的Checkpointed at scn相同了。表示刚才的恢复实现了Checkpointed at scn的同步）

 thread:1 rba:(0x1c.17.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000  00000000 00000000

Backup Checkpointed at scn:  0x0000.00000000

 thread:0 rba:(0x0.0.0)

 enabled  threads:  00000000 00000000 00000000 00000000 00000000 00000000  00000000 00000000

External cache id: 0x0 0x0 0x0 0x0

Absolute fuzzy scn: 0x0000.00000000

Recovery fuzzy scn: 0x0000.00000000 08/10/2006 15:57:01

Terminal Recovery Stamp scn: 0x0000.00000000 01/01/1988 00:00:00

 

也贴出dump控制文件的信息：

 

SQL> alter session set events 'immediate trace name CONTROLF level 10';

Session altered.

 

***********************************************************

DATA FILE #11:

  (name #15) /opt/oracle/oradata/cicro/cicrodb.dbf

creation size=1280 block size=8192 status=0xe head=15 tail=15 dup=1

 tablespace 12, index=12 krfil=11 prev_file=0

 unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00

 Checkpoint cnt:141 scn: 0x0800.0195c773 08/10/2006 15:57:01

 Stop scn: 0x0800.0195c771 08/10/2006 15:57:01

 Creation Checkpointed at scn:  0x0000.01213333 12/28/2005 15:28:58

 thread:1 rba:(0x60.baf.10)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

 Offline scn: 0x0800.017b052f prev_range: 0

 Online Checkpointed at scn:  0x0800.017b0530 08/02/2006 02:29:36

 thread:1 rba:(0x1.2.0)

 enabled  threads:  01000000 00000000 00000000 00000000 00000000 00000000  00000000 00000000

 Hot Backup end marker scn: 0x0000.00000000

 aux_file is NOT DEFINED

 

 

最后数据库可以顺利open

 

SQL> alter database open;

Database altered.

 

 

 

我们可以想象，如果控制文件是从备份中恢复的，那么数据库在open过程中又将如何呢?

首先备份控制文件，打开数据库，增进检查点: 

[oracle@jumper eygle]$ cp control01.ctl control01.ctl.bak [oracle@jumper eygle]$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Fri Aug 11 10:46:05 2006 Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved. Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area  139531744 bytes Fixed Size                   452064 bytes Variable Size             121634816 bytes Database Buffers           16777216 bytes Redo Buffers                 667648 bytes Database mounted. Database opened. SQL> alter system checkpoint; System altered. SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> exit Disconnected from Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production With the Partitioning option JServer Release 9.2.0.4.0 - Production

然后恢复旧的控制文件，mount数据库，转储数据文件头:

[oracle@jumper eygle]$ mv control01.ctl control01.ctl.n [oracle@jumper eygle]$ mv control01.ctl.bak control01.ctl [oracle@jumper eygle]$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Fri Aug 11 10:46:50 2006 Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved. Connected to an idle instance. SQL> startup mount; ORACLE instance started. Total System Global Area  139531744 bytes Fixed Size                   452064 bytes Variable Size             121634816 bytes Database Buffers           16777216 bytes Redo Buffers                 667648 bytes Database mounted. SQL> alter session set events 'immediate trace name file_hdrs level 10'; Session altered. SQL> !

我们看控制文件的信息（选择一个文件）:

DATA FILE #4:   (name #4) /opt/oracle/oradata/eygle/eygle01.dbf creation size=0 block size=8192 status=0xe head=4 tail=4 dup=1  tablespace 4, index=4 krfil=4 prev_file=0  unrecoverable scn: 0x0000.00000000 01/01/1988 00:00:00  Checkpoint cnt:61 scn: 0x0000.002acb1e 08/11/2006 10:44:38  Stop scn: 0x0000.002acb1e 08/11/2006 10:44:38  Creation Checkpointed at scn:  0x0000.0015078d 06/06/2006 09:41:54

再看数据文件头信息:

FILE HEADER:         Software vsn=153092096=0x9200000, Compatibility Vsn=134217728=0x8000000         Db ID=1407686520=0x53e79778, Db Name='EYGLE'         Activation ID=0=0x0         Control Seq=989=0x3dd, File size=1280=0x500         File Number=4, Blksiz=8192, File Type=3 DATA Tablespace #4 - EYGLE  rel_fn:4 Creation   at   scn: 0x0000.0015078d 06/06/2006 09:41:54 Backup taken at scn: 0x0000.00000000 01/01/1988 00:00:00 thread:0  reset logs count:0x232bee1f scn: 0x0000.0007c781 recovered at 08/11/2006 10:11:26  status:0x0 root dba:0x00000000 chkpt cnt: 64 ctl cnt:63 begin-hot-backup file size: 0 Checkpointed at scn:  0x0000.002acb98 08/11/2006 10:46:24

我们注意到数据文件的chkpt cnt: 64 要大于控制文件的Checkpoint cnt:61，也就是说控制文件是旧的。

此时尝试打开数据库就会出现如下错误:

[oracle@jumper udump]$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Fri Aug 11 10:51:20 2006 Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production With the Partitioning option JServer Release 9.2.0.4.0 - Production SQL> alter database open; alter database open * ERROR at line 1: ORA-01122: database file 1 failed verification check ORA-01110: data file 1: '/opt/oracle/oradata/eygle/system01.dbf' ORA-01207: file is more recent than controlfile - old controlfile

Oracle告诉我们，控制文件是旧的。此时我们可以通过重建控制文件或者从旧的数据备份开始恢复。