SNAPSHOT CONTROLFILE有什么用途

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根据我的理解：
snapshot control file只有在同步catalog的时候用到或者在控制文件备份的时候用到
（在备份控制文件之前会备份一个 SNAPSHOT CONTROLFILE ）
----------------------------------------------------------
SNAPSHOT CONTROLFILE 的用途，顾名思义，应该是用来恢复控制文件的，下面是我的测试结果：
结论是：
1.SNAPSHOT CONTROLFILE 不能直接copy成control file，如果数据库已经shutdown
2.可以通过rman，将SNAPSHOT CONTROLFILE 恢复成控制文件
3.如果数据库没有shutdown，可以直接copy SNAPSHOT CONTROLFILE 成控制文件，但仍需要恢复（因为他是旧的）

下面是我的测试步骤：
---------------------------------------
查看snapshot controlfile的备份设置:
RMAN> SHOW SNAPSHOT CONTROLFILE NAME;

RMAN configuration parameters are:
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/ora9a/product/9.2/dbs/snapcf_tt9a.f'; # default

RMAN>

下面模拟控制文件丢失的恢复
$ ls
control01.ctl  cwmlite01.dbf  indx01.dbf     redo02.log     temp01.dbf     users01.dbf
control02.ctl  drsys01.dbf    odm01.dbf      redo03.log     tools01.dbf    xdb01.dbf
control03.ctl  example01.dbf  redo01.log     system01.dbf   undotbs01.dbf
$ rm cont*  --删除控制文件
$ ls
cwmlite01.dbf  example01.dbf  odm01.dbf      redo02.log     system01.dbf   tools01.dbf    users01.dbf
drsys01.dbf    indx01.dbf     redo01.log     redo03.log     temp01.dbf     undotbs01.dbf  xdb01.dbf
$
在控制文件被删除后，数据库还能正常操作：
sql> insert into test(no) values(4);

1 row created.

SQL> commit;

Commit complete.

SQL> alter system switch logfile;

System altered.

SQL> alter system checkpoint;

System altered.

SQL> /

System altered.

SQL>
SQL> select no,to_char(vdate,'yyyy-mm-dd hh34:mi:ss') from  test;

NO TO_CHAR(VDATE,'YYYY-MM-DDHH24:MI:SS')
---------- ---------------------------------------------------------
        1 2009-02-24 10:16:09
        2 2009-02-24 10:25:30
        3 2009-02-24 10:26:56
        4 2009-02-24 10:30:59

SQL>
重新启动数据库：
SQL> connect /as sysdba
Connected.
SQL> shutdown immediate
ORA-00210: cannot open the specified controlfile
ORA-00202: controlfile: '/u01/ora9a/oradata/tt9a/control01.ctl'
ORA-27041: unable to open file
IBM aiX RISC System/6000 Error: 2: No such file or directory
Additional infORMation: 3
没有了控制文件了，shutdown immediate出错
SQL>
SQL> shutdown abort;
oracle instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  320569400 bytes
Fixed Size                   741432 bytes
Variable Size             285212672 bytes
Database Buffers           33554432 bytes
Redo Buffers                1060864 bytes
ORA-00205: error in identifying controlfile, check alert log for more info

SQL>
没有控制文件，数据库不能mount，现在把SNAPSHOT CONTROLFILE copy到对应目录
$ cp /u01/ora9a/product/9.2/dbs/snapcf_tt9a.f /u01/ora9a/oradata/tt9a/control01.ctl
$ cp /u01/ora9a/oradata/tt9a/control01.ctl /u01/ora9a/oradata/tt9a/control0t.ctl
$ cp /u01/ora9a/oradata/tt9a/control01.ctl /u01/ora9a/oradata/tt9a/control03.ctl
$ ls -lrt /u01/ora9a/oradata/tt9a/contr*      
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:36 /u01/ora9a/oradata/tt9a/control01.ctl
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:36 /u01/ora9a/oradata/tt9a/control0t.ctl
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:36 /u01/ora9a/oradata/tt9a/control03.ctl
$
SQL> startup
ORACLE instance started.

Total System Global Area  320569400 bytes
Fixed Size                   741432 bytes
Variable Size             285212672 bytes
Database Buffers           33554432 bytes
Redo Buffers                1060864 bytes
ORA-00205: error in identifying controlfile, check alert log for more info
照样不能mount数据库
----------------------------------------
尝试用rman恢复控制文件:
$ rman target /

Recovery Manager: Release 9.2.0.1.0 - 64bit Production

Copyright (c) 1995, 2002, Oracle Corporation.  All rights reserved.

connected to target database (not started)

RMAN> startup nomount;

Oracle instance started

Total System Global Area     320569400 bytes

Fixed Size                      741432 bytes
Variable Size                285212672 bytes
Database Buffers              33554432 bytes
Redo Buffers                   1060864 bytes

RMAN>  restore controlfile from '/u01/ora9a/product/9.2/dbs/snapcf_tt9a.f';

Starting restore at 24-FEB-09

using target database controlfile instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=13 devtype=DISK
channel ORA_DISK_1: copied controlfile copy
replicating controlfile
input filename=/u01/ora9a/oradata/tt9a/control01.ctl
output filename=/u01/ora9a/oradata/tt9a/control02.ctl
output filename=/u01/ora9a/oradata/tt9a/control03.ctl
Finished restore at 24-FEB-09

RMAN> alter database mount;

database mounted

RMAN>
ok,用rman可以进行恢复，让数据mount起来
恢复数据库
RMAN> recover database;

Starting recover at 24-FEB-09
using channel ORA_DISK_1

starting media recovery

arcHive log thread 1 sequence 1 is already on disk as file /u01/ora9a/oradata/tt9a/redo01.log
archive log thread 1 sequence 2 is already on disk as file /u01/ora9a/oradata/tt9a/redo02.log
archive log thread 1 sequence 3 is already on disk as file /u01/ora9a/oradata/tt9a/redo03.log
archive log filename=/u01/ora9a/oradata/tt9a/redo01.log thread=1 sequence=0
archive log filename=/u01/ora9a/oradata/tt9a/redo02.log thread=1 sequence=2
archive log filename=/u01/ora9a/oradata/tt9a/redo03.log thread=1 sequence=3
media recovery complete
Finished recover at 24-FEB-09

RMAN> alter database open;

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of alter db command at 02/24/2009 10:47:36
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

RMAN> alter database open resetlogs;

database opened

RMAN>
查看先前insert的数据：
SQL> select no,to_char(vdate,'yyyy-mm-dd hh34:mi:ss') from  test;

NO TO_CHAR(VDATE,'YYYY-MM-DDHH24:MI:SS')
---------- ---------------------------------------------------------
        1 2009-02-24 10:16:09
        2 2009-02-24 10:25:30
        3 2009-02-24 10:26:56
        4 2009-02-24 10:30:59

SQL>
数据仍在，恢复成功!

=============================
下面仍是在数据库正常运行情况下，将控制文件删除，仍测试直接copy SNAPSHOT CONTROLFILE 的恢复方式：
SQL> insert into test(no) values(5);

1 row created.

SQL> commit;

Commit complete.

SQL>
SQL> !
$ pwd
/u01/ora9a/oradata/tt9a
$ ls
control01.ctl  control0t.ctl  example01.dbf  redo01.log     system01.dbf   undotbs01.dbf
control02.ctl  cwmlite01.dbf  indx01.dbf     redo02.log     temp01.dbf     users01.dbf
control03.ctl  drsys01.dbf    odm01.dbf      redo03.log     tools01.dbf    xdb01.dbf
$ rm contr*
$ ls
cwmlite01.dbf  example01.dbf  odm01.dbf      redo02.log     system01.dbf   tools01.dbf    users01.dbf
drsys01.dbf    indx01.dbf     redo01.log     redo03.log     temp01.dbf     undotbs01.dbf  xdb01.dbf
$
$ exit

SQL> select * from v$controlfile;

STATUS
---------------------
NAME
--------------------------------------------------------------------------------

/u01/ora9a/oradata/tt9a/control01.ctl

/u01/ora9a/oradata/tt9a/control02.ctl

/u01/ora9a/oradata/tt9a/control03.ctl

SQL> select dbid from v$database;
select dbid from v$database
                *
ERROR at line 1:
ORA-00210: cannot open the specified controlfile
ORA-00202: controlfile: '/u01/ora9a/oradata/tt9a/control01.ctl'
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 2: No such file or directory
Additional information: 3

SQL>
没有控制文件，查询失败
现在将SNAPSHOT CONTROLFILE copy到对应目录，尝试直接恢复成控制文件:
SQL> !
$ pwd
/u01/ora9a/oradata/tt9a
$ cp  /u01/ora9a/product/9.2/dbs/snapcf_tt9a.f  control01.ctl
$ cp control01.ctl control02.ctl
$ cp control01.ctl control03.ctl
$ ls -lrt cont*
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:55 control01.ctl
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:55 control02.ctl
-rw-r-----   1 ora9a    dba         1531904 Feb 24 10:55 control03.ctl
$
注意，此时不要起停数据库，否则这样恢复的控制文件仍不可用
尝试查询control file信息
SQL> select dbid from v$database;

DBID
----------
3459515476

SQL>
ok,成功
查询数据文件头信息
SQL> select CHECKPOINT_CHANGE#   from v$datafile_header;
select CHECKPOINT_CHANGE#   from v$datafile_header
                                *
ERROR at line 1:
ORA-00600: internal error code, arguments: [2170], [], [], [], [], [], [], []

SQL>
失败
现在重新启动数据库，看看是否可以到mount状态：
SQL> shutdown immediate
ORA-00600: internal error code, arguments: [kccchb_1], [356], [353], [0], [353], [0], [], []
SQL> shutdown abort;
ORACLE instance shut down.
SQL>
SQL> startup
ORACLE instance started.

Total System Global Area  320569400 bytes
Fixed Size                   741432 bytes
Variable Size             285212672 bytes
Database Buffers           33554432 bytes
Redo Buffers                1060864 bytes
Database mounted.
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

SQL>
ok，此时数据库可以mount起来了

SQL>
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;
alter database open resetlogs
*
ERROR at line 1:
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/u01/ora9a/oradata/tt9a/system01.dbf'
提示需要恢复
SQL> recover database using backup controlfile;
ORA-00279: change 349227 generated at 02/24/2009 10:49:58 needed for thread 1
ORA-00289: suggestion : /u01/arch/1_1.dbf
ORA-00280: change 349227 for thread 1 is in sequence #1

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
AUTO
ORA-00328: archived log ends at change 347581, need later change 349227
ORA-00334: archived log: '/u01/arch/1_1.dbf'

SQL> recover database using backup controlfile;
ORA-00279: change 349227 generated at 02/24/2009 10:49:58 needed for thread 1
ORA-00289: suggestion : /u01/arch/1_1.dbf
ORA-00280: change 349227 for thread 1 is in sequence #1

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
/u01/ora9a/oradata/tt9a/redo01.log
Log applied.
Media recovery complete.

SQL> alter database open resetlogs;

Database altered.

SQL>
恢复成功
SQL> select no,to_char(vdate,'yyyy-mm-dd hh34:mi:ss') from  test order by vdate;

NO TO_CHAR(VDATE,'YYYY-MM-DDHH24:MI:SS')
---------- ---------------------------------------------------------
        1 2009-02-24 10:16:09
        2 2009-02-24 10:25:30
        3 2009-02-24 10:26:56
        4 2009-02-24 10:30:59
        5 2009-02-24 10:51:01

SQL>
ok,新插入的数据也在。

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