Oracle在线 redo log文件丢失后的恢复

今天一个开发库启动不了了，发过来报错一看是日志文件损坏了(见下图)，接着说了一下前因后果。说是年前服务器掉电了，然后就再没有启动起来过。今天有人用才想到要处理。

先说一下大体的思路，如果损坏的redo log是INACTIVE状态的，也就是实例崩溃恢复用不到的redo log，那处理起来比较容易，直接alter database clear logfile group #;或alter database clear unarchived logfile group #;重建日志组就行了。建议重建日志文件级后对数据库做一个全库备份，特别是强制clear后，造成的归档日志文件断层。在如果损坏的redo log是ACTIVE或CURRENT状态的，也就是实例崩溃恢复需要用到的redo log，那处理起来就比较麻烦了，损坏这种redo log就意味着丢失数据。

redo log的三种状态：

• INACTIVE：日志对应的修改已经被写入硬盘

• ACTIVE：日志对应的修改还没有被写入硬盘

• CURRENT：实例正在使用的日志文件

由于这个开发库有种种的问题，恢复起来遇到了各种情况，这里用一个虚拟机上的数据库演示如果CURRENT或ACTIVE状态的日志文件损坏的情况下如何恢复。

1、构造场景

删除一张表的数据但不提交，然后在另一个会话中把数据库shutdown abort。再删除所有的redo log文件。

#session 1sys@ORCL>delete from zx;2858 rows deleted.#session 2sys@ORCL>select group#,status from v$log;    GROUP# STATUS---------- ------------------------------------------------         1 INACTIVE         2 ACTIVE         3 CURRENTsys@ORCL>shutdown abort;ORACLE instance shut down.#删除redo log文件[oracle@rhel6 ~]$ cd /u02/app/oracle/oradata/orcl/[oracle@rhel6 orcl]$ ls -l  total 1944992-rw-r----- 1 oracle oinstall   9748480 Feb 24 23:56 control01.ctl-rw-r----- 1 oracle oinstall   9748480 Feb 24 23:56 control02.ctl-rw-r----- 1 oracle oinstall 328343552 Feb 24 23:54 example01.dbf-rw-r----- 1 oracle oinstall  52429312 Feb 24 23:54 redo01.log-rw-r----- 1 oracle oinstall  52429312 Feb 24 23:55 redo02.log-rw-r----- 1 oracle oinstall  52429312 Feb 24 23:55 redo03.log-rw-r----- 1 oracle oinstall 545267712 Feb 24 23:54 sysaux01.dbf-rw-r----- 1 oracle oinstall 796925952 Feb 24 23:54 system01.dbf-rw-r----- 1 oracle oinstall  30416896 Feb 24 13:58 temp01.dbf-rw-r----- 1 oracle oinstall 110108672 Feb 24 23:54 undotbs01.dbf-rw-r----- 1 oracle oinstall   5251072 Feb 24 23:54 users01.dbf[oracle@rhel6 orcl]$ rm redo*logl[oracle@rhel6 orcl]$ ls -ltotal 1791212-rw-r----- 1 oracle oinstall   9748480 Feb 24 23:56 control01.ctl-rw-r----- 1 oracle oinstall   9748480 Feb 24 23:56 control02.ctl-rw-r----- 1 oracle oinstall 328343552 Feb 24 23:54 example01.dbf-rw-r----- 1 oracle oinstall 545267712 Feb 24 23:54 sysaux01.dbf-rw-r----- 1 oracle oinstall 796925952 Feb 24 23:54 system01.dbf-rw-r----- 1 oracle oinstall  30416896 Feb 24 13:58 temp01.dbf-rw-r----- 1 oracle oinstall 110108672 Feb 24 23:54 undotbs01.dbf-rw-r----- 1 oracle oinstall   5251072 Feb 24 23:54 users01.dbf

2、启动数据库出现报错

idle>startup ORACLE instance started.Total System Global Area 1603411968 bytesFixed Size             2253664 bytesVariable Size               1476398240 bytesDatabase Buffers     117440512 bytesRedo Buffers                   7319552 bytesDatabase mounted.ORA-00313: open failed for members of log group 2 of thread 1ORA-00312: online log 2 thread 1: '/u02/app/oracle/oradata/orcl/redo02.log'ORA-27037: unable to obtain file statusLinux-x86_64 Error: 2: No such file or directoryAdditional information: 3

3、尝试使用clear方式重建日志组出现报错

idle>alter database clear logfile group 2;alter database clear logfile group 2*ERROR at line 1:ORA-01624: log 2 needed for crash recovery of instance orcl (thread 1)ORA-00312: online log 2 thread 1: '/u02/app/oracle/oradata/orcl/redo02.log'idle>alter database clear unarchived logfile group 2;alter database clear unarchived logfile group 2*ERROR at line 1:ORA-01624: log 2 needed for crash recovery of instance orcl (thread 1)ORA-00312: online log 2 thread 1: '/u02/app/oracle/oradata/orcl/redo02.log'

从报错信息中可以看出log 2是实例崩溃恢复所需要的日志文件，不能直接重建。

4、这种情况下使用隐含参数_allow_resetlogs_corruption，创建pfile，把*._allow_resetlogs_corruption=TRUE加入到pfile中。然后mount数据库，强制不完全恢复，再open resetlogs

idle>create pfile='/home/oracle/initorcl.ora' from spfile;File created.[oracle@rhel6 orcl]$ vi /home/oracle/initorcl.ora idle>shutdown immediate;ORA-01109: database not openDatabase dismounted.ORACLE instance shut down.idle>startup pfile='/home/oracle/initorcl.ora' mount;ORACLE instance started.Total System Global Area 1603411968 bytesFixed Size             2253664 bytesVariable Size               1476398240 bytesDatabase Buffers     117440512 bytesRedo Buffers                   7319552 bytesDatabase mounted.idle>show parameter _allow_NAME                                 TYPE                             VALUE------------------------------------ --------------------------------- ------------------------------_allow_resetlogs_corruption          boolean                          TRUEidle>recover database until cancel;ORA-00279: change 1023441 generated at 02/24/2017 23:54:54 needed for thread 1ORA-00289: suggestion : /u02/app/oracle/product/11.2.4/db1/dbs/arch2_2_936817668.dbfORA-00280: change 1023441 for thread 1 is in sequence #2Specify log: {=suggested | filename | AUTO | CANCEL}cancelORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error belowORA-01194: file 1 needs more recovery to be consistentORA-01110: data file 1: '/u02/app/oracle/oradata/orcl/system01.dbf'ORA-01112: media recovery not startedidle>alter database open resetlogs;Database altered.idle>select open_mode from v$database;OPEN_MODE------------------------------------------------------------READ WRITE

可以看到现在数据库已经被open了。

5、再次查看第一步中被删除的数据的表，数据仍然存在说明丢失CURRENT或ACTIVE状态的日志文件会导致数据丢失。

idle>select count(*) from zx;  COUNT(*)----------      2858

以上是在虚拟机上做测试的恢复过程，但是对于前面说到的开发库的恢复就没有这个过程简单了。可以说是解决了一个报错又出来新的报错。

在使用_allow_resetlogs_corruption参数执行不完全恢复，open resetlogs 时，遇到了ORA-01248

SQL> alter database open resetlogs;alter database open resetlogs*ERROR at line 1:ORA-01248: file 5 was created in the future of incomplete recovery

于是先把这个文件offline drop

SQL> alter database datafile 5 offline drop;

再次open resetlogs时又遇到了ORA-00704和ORA-01555

SQL> alter database open resetlogs;alter database open resetlogs*ERROR at line 1:ORA-01092: ORACLE instance terminated. Disconnection forcedORA-00704: bootstrap process failureORA-00704: bootstrap process failureORA-00604: error occurred at recursive SQL level 1ORA-01555: snapshot too old: rollback segment number 5 with name"_SYSSMU5_4116806824$" too smallProcess ID: 3396Session ID: 573 Serial number: 51

由于现在的水平有限，在网上查资料也没有能解决这一系列的问题，最后没办法只能重建库，重新导数据了。

如果哪位遇到了类似的问题，而且解决了，也请分享一下经验。

其实上午在模拟这个问题的时候，在open resetlogs时还遇到了一个经典的报错ORA-600 [2662]，这个错误可以参考eygle的博客http://www.eygle.com/archives/2005/12/oracle_diagnostics_howto_deal_2662_error.html

参考：http://iquicksandi.blog.163.com/blog/static/13228526220107642655204/

http://www.linuxidc.com/Linux/2012-02/53426.htm

http://www.killdb.com/2014/06/19/%E6%95%B0%E6%8D%AE%E5%BA%93open%E6%8A%A5%E9%94%99ora-01555-snapshot-too-old.html

http://www.askmaclean.com/archives/%E3%80%90oracle%E6%81%A2%E5%A4%8D%E3%80%91ora-704.html