current online redo logfile 丢失的处理方法

昨天做了rm -rf操作后的恢复演练，而且是在没有任何备份的情况下。今天在做破坏性操作前，做了个rman全备，然后在线删除全部数据库文件，包括控制文件，数据文件，在线日志文件，归档文件等。来看看有什么方法可以让数据库恢复运行，由于是current redo logfile丢失，那么本次测试是会丢失数据的，所以可以作为不完全恢复的一个案例。

--登入数据库进行dml操作

[oracle@ora10g ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Aug 26 13:40:37 2014

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

SQL> select * from aaron8219.test1;

INT

----------

1

2

SQL> insert into aaron8219.test1 values(3);

1 row created.

SQL> select group#,status,sequence# from v$log;

GROUP# STATUS SEQUENCE#

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

1 INACTIVE 1

2 CURRENT 2

3 INACTIVE 0

--不提交，另开一个session进行rm -rf操作

[root@ora10g ~]# cd /u01/app/oracle/oradata

[root@ora10g oradata]# ll

total 4

drwxr-x--- 2 oracle oinstall 4096 Aug 25 16:09 ora10g

[root@ora10g oradata]# rm -rf ora10g/

[root@ora10g oradata]# ll

total 0

--原session直接abort关闭，模拟current online redo logfile丢失

SQL> shutdown abort

--用之前刚生成的rman全备来还原数据库各类文件

[oracle@ora10g ~]$ rman target /

Recovery Manager: Release 10.2.0.1.0 - Production on Tue Aug 26 13:44:58 2014

Copyright (c) 1982, 2005, Oracle. All rights reserved.

connected to target database: ora10g (not mounted)

RMAN> restore controlfile from '/rmanbak/full_ORA10G_4175411955_20140826_02pgtq5h_1_1.bak';

Starting restore at 26-AUG-14

using channel ORA_DISK_1

channel ORA_DISK_1: restoring control file

channel ORA_DISK_1: restore complete, elapsed time: 00:00:04

output filename=/u01/app/oracle/oradata/ora10g/control01.ctl

output filename=/u01/app/oracle/oradata/ora10g/control02.ctl

output filename=/u01/app/oracle/oradata/ora10g/control03.ctl

Finished restore at 26-AUG-14

RMAN> alter database mount;

database mounted

released channel: ORA_DISK_1

RMAN> restore database;

Starting restore at 26-AUG-14

Starting implicit crosscheck backup at 26-AUG-14

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=156 devtype=DISK

Crosschecked 1 objects

Finished implicit crosscheck backup at 26-AUG-14

Starting implicit crosscheck copy at 26-AUG-14

using channel ORA_DISK_1

Finished implicit crosscheck copy at 26-AUG-14

searching for all files in the recovery area

cataloging files...

cataloging done

List of Cataloged Files

=======================

File Name: /u01/app/oracle/flash_recovery_area/ORA10G/autobackup/2014_08_26/o1_mf_s_856615092_9zr3snsq_.bkp

using channel ORA_DISK_1

channel ORA_DISK_1: starting datafile backupset restore

channel ORA_DISK_1: specifying datafile(s) to restore from backup set

restoring datafile 00001 to /u01/app/oracle/oradata/ora10g/system01.dbf

restoring datafile 00002 to /u01/app/oracle/oradata/ora10g/undotbs01.dbf

restoring datafile 00003 to /u01/app/oracle/oradata/ora10g/sysaux01.dbf

restoring datafile 00004 to /u01/app/oracle/oradata/ora10g/users01.dbf

restoring datafile 00005 to /u01/app/oracle/oradata/ora10g/example01.dbf

channel ORA_DISK_1: reading from backup piece /rmanbak/full_ORA10G_4175411955_20140826_01pgtq36_1_1.bak

channel ORA_DISK_1: restored backup piece 1

piece handle=/rmanbak/full_ORA10G_4175411955_20140826_01pgtq36_1_1.bak tag=TAG20140826T123653

channel ORA_DISK_1: restore complete, elapsed time: 00:01:46

Finished restore at 26-AUG-14

RMAN> exit

Recovery Manager complete.

由于rman并不备份在线日志文件，刚才的rman只是做了个全库备份和控制文件的备份，可以看到redo01.log，redo02.log，redo03.log这3个文件并不存在

[oracle@ora10g ~]$ sqlplus / as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Tue Aug 26 14:52:35 2014

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

SQL> select open_mode from v$database;

OPEN_MODE

----------

MOUNTED

SQL> col member for a60

SQL> select group#,member from v$logfile;

GROUP# MEMBER

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

3 /u01/app/oracle/oradata/ora10g/redo03.log

2 /u01/app/oracle/oradata/ora10g/redo02.log

1 /u01/app/oracle/oradata/ora10g/redo01.log

SQL> alter database open resetlogs;

alter database open resetlogs

*

ERROR at line 1:

ORA-01152: file 1 was not restored from a sufficiently old backup

ORA-01110: data file 1: '/u01/app/oracle/oradata/ora10g/system01.dbf'

由于只是restore了数据库，还未recover，数据库是无法打开的

SQL> recover database

ORA-00283: recovery session canceled due to errors

ORA-01610: recovery using the BACKUP CONTROLFILE option must be done

SQL> recover database until cancel;

ORA-00283: recovery session canceled due to errors

ORA-01610: recovery using the BACKUP CONTROLFILE option must be done

SQL> recover database using backup controlfile;

ORA-00279: change 502729 generated at 08/26/2014 15:36:54 needed for thread 1

ORA-00289: suggestion :

/u01/app/oracle/flash_recovery_area/ORA10G/archivelog/2014_08_26/o1_mf_1_3_%u_.arc

ORA-00280: change 502729 for thread 1 is in sequence #3

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

auto

ORA-00308: cannot open archived log

'/u01/app/oracle/flash_recovery_area/ORA10G/archivelog/2014_08_26/o1_mf_1_3_%u_.arc'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

ORA-00308: cannot open archived log

'/u01/app/oracle/flash_recovery_area/ORA10G/archivelog/2014_08_26/o1_mf_1_3_%u_.arc'

ORA-27037: unable to obtain file status

Linux Error: 2: No such file or directory

Additional information: 3

SQL> recover database using backup controlfile until cancel;

ORA-00279: change 502729 generated at 08/26/2014 15:36:54 needed for thread 1

ORA-00289: suggestion :

/u01/app/oracle/flash_recovery_area/ORA10G/archivelog/2014_08_26/o1_mf_1_3_%u_.arc

ORA-00280: change 502729 for thread 1 is in sequence #3

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

cancel

Media recovery cancelled.

SQL>

由于之前的归档没有用rman备份，而现在也不存在了，无法recover数据库，就算用resetlogs也无法open数据库。此时，只有通过隐含参数_allow_resetlogs_corruption来open数据库了

SQL> show parameter spfile

NAME TYPE VALUE

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

spfile string /u01/app/oracle/product/10.2.0

/db_1/dbs/spfileora10g.ora

--创建pfile

SQL> create pfile from spfile;

File created.

--编辑$ORACLE_HOME/dbs/initora10g.ora初始化参数文件，在文件末尾添加*._allow_resetlogs_corruption = true

[oracle@ora10g ora10g]$ vi $ORACLE_HOME/dbs/initora10g.ora

ora10g.__db_cache_size=180355072

ora10g.__java_pool_size=4194304

ora10g.__large_pool_size=4194304

ora10g.__shared_pool_size=92274688

ora10g.__streams_pool_size=0

*.audit_file_dest='/u01/app/oracle/admin/ora10g/adump'

*.background_dump_dest='/u01/app/oracle/admin/ora10g/bdump'

*.compatible='10.2.0.1.0'

*.control_files='/u01/app/oracle/oradata/ora10g/control01.ctl','/u01/app/oracle/oradata/ora10g/control02.ctl','/u01/app/oracle/oradata/ora10g/control03.ctl'#Restore Controlfile

*.core_dump_dest='/u01/app/oracle/admin/ora10g/cdump'

*.db_block_size=8192

*.db_domain=''

*.db_file_multiblock_read_count=16

*.db_name='ora10g'

*.db_recovery_file_dest='/u01/app/oracle/flash_recovery_area'

*.db_recovery_file_dest_size=2147483648

*.dispatchers='(PROTOCOL=TCP) (SERVICE=ora10gXDB)'

*.job_queue_processes=10

*.log_archive_format='%t_%s_%r.dbf'

*.nls_language='SIMPLIFIED CHINESE'

*.nls_territory='CHINA'

*.open_cursors=300

*.pga_aggregate_target=94371840

*.processes=150

*.remote_login_passwordfile='EXCLUSIVE'

*.sga_target=285212672

*.undo_management='AUTO'

*.undo_tablespace='UNDOTBS1'

*.user_dump_dest='/u01/app/oracle/admin/ora10g/udump'

*._allow_resetlogs_corruption=TRUE

--关闭数据库实例，用pfile启动

SQL> shutdown immediate

ORA-01109: database not open

Database dismounted.

ORACLE instance shut down.

SQL> startup pfile=$ORACLE_HOME/dbs/initora10g.ora

ORACLE instance started.

Total System Global Area 285212672 bytes

Fixed Size 1218992 bytes

Variable Size 100664912 bytes

Database Buffers 180355072 bytes

Redo Buffers 2973696 bytes

Database mounted.

ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

--最后用resetlogs打开数据库

SQL> alter database open resetlogs;

Database altered.

SQL>

[oracle@ora10g ora10g]$ ll

total 1051020

-rw-r----- 1 oracle oinstall 7061504 Aug 26 16:03 control01.ctl

-rw-r----- 1 oracle oinstall 7061504 Aug 26 16:03 control02.ctl

-rw-r----- 1 oracle oinstall 7061504 Aug 26 16:03 control03.ctl

-rw-r----- 1 oracle oinstall 104865792 Aug 26 16:03 example01.dbf

-rw-r----- 1 oracle oinstall 52429312 Aug 26 16:03 redo01.log

-rw-r----- 1 oracle oinstall 52429312 Aug 26 16:03 redo02.log

-rw-r----- 1 oracle oinstall 52429312 Aug 26 16:03 redo03.log

-rw-r----- 1 oracle oinstall 251666432 Aug 26 16:03 sysaux01.dbf

-rw-r----- 1 oracle oinstall 503324672 Aug 26 16:03 system01.dbf

-rw-r----- 1 oracle oinstall 20979712 Aug 26 16:03 temp01.dbf

-rw-r----- 1 oracle oinstall 31465472 Aug 26 16:03 undotbs01.dbf

-rw-r----- 1 oracle oinstall 5251072 Aug 26 16:03 users01.dbf

[oracle@ora10g ora10g]$

再次查看数据文件，发现重新生成了3个online redo logfile了

--resetlogs把SEQUENCE#序列号重新变成1

SQL> select group#,sequence# from v$log;

GROUP# SEQUENCE#

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

1 0

2 1

3 0

--测试表只留下了原来的数据库，因为没有commit，新插入的第3条记录丢失，就算commit，也是会丢数据的，因为redo logfile也被删除了

SQL> select * from aaron8219.test1;

INT

----------

1

2

注意，最后要把刚才设置的隐含参数_allow_resetlogs_corruption = true去掉，并重新创建spfile，否则数据库将来会有引起不一致的风险，设置该隐含参数只是下下策，为了能让数据库open而不得已为之，丢失数据库是肯定的了，因为这是在极端情况下得测试，通常只有在丢失了状态为current的online redo logfile才会丢失数据，如果只是inactive的redo logfile，就算使用alter database
open resetlogs;也不意味着100%丢数据。另外，要注意的是，当使用using backup controlfile关键词时，必须要配合使用open resetlogs来打开数据库。以resetlogs方式open数据库后，必须重新做一次数据库全备，因为一旦incarnation改变之后，数据库原来的备份集就失效了。