记录8.0.5数据库恢复过程

某银行需要恢复2004年磁带备份数据库 8.0.5,当时因为开发商使用begin backup命令进行热备,然后压缩到磁带上.在硬盘紧张,rman不成熟的时代,使用这样的方法备份本身没有大问题,可是因为没有备份归档日志,给现在的恢复带来了很多的问题.
尝试不完全恢复启动库

SVRMGR> startup pfile='init.ora' mount
ORACLE instance started.
Total System Global Area                        141826208 bytes
Fixed Size                                          47264 bytes
Variable Size                                   124829696 bytes
Database Buffers                                 16777216 bytes
Redo Buffers                                       172032 bytes
Database mounted.
SVRMGR> recover database using backup controlfile until cancel;
ORA-00279: change 613561556 generated at 08/21/04 22:42:48 needed for thread 1
ORA-00289: suggestion : /oracle/product/8.0.5/dbs/arch1_55329.dbf
ORA-00280: change 613561556 for thread 1 is in sequence #55329
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
SVRMGR> alter database open resetlogs;
alter database open resetlogs
*
ORA-00600: internal error code, arguments: [4146], [31400], [31370], [], [], [], [], []

这个错误是因为回滚段corruption导致,客户已经没有了一致性要求,所以解决办法是通过一些手段找出回滚段并屏蔽

屏蔽回滚段重启库

SVRMGR> shutdown abort
ORACLE instance shut down.
SVRMGR> startup  pfile='init.ora' mount
ORACLE instance started.
Total System Global Area                        141826208 bytes
Fixed Size                                          47264 bytes
Variable Size                                   124829696 bytes
Database Buffers                                 16777216 bytes
Redo Buffers                                       172032 bytes
Database mounted.
SVRMGR> alter database open;
alter database open
*
ORA-00600: internal error code, arguments: [3668], [1], [2], [55992], [55992], [4], [], []

根据ORA-00600[3668]错误的提示,因为重建控制文件,有一个数据文件因为在磁带恢复丢失,所以控制文件在上次重建的时候没有包含进去,根据经验在8.0中可以通过resetlogs解决

resetlogs重新打开数据库

SVRMGR> alter database open resetlogs;
alter database open resetlogs
*
ORA-01139: RESETLOGS option only valid after an incomplete database recovery
SVRMGR> recover datatabase using backup controlfile until cancel;
ORA-00274: illegal recovery option DATATABASE
SVRMGR> recover database using backup controlfile until cancel;
ORA-00279: change 613561558 generated at 07/30/12 09:14:49 needed for thread 1
ORA-00289: suggestion : /oracle/product/8.0.5/dbs/arch1_1.dbf
ORA-00280: change 613561558 for thread 1 is in sequence #1
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
SVRMGR> alter database open resetlogs;
alter database open resetlogs
*
ORA-00604: error occurred at recursive SQL level 1
ORA-01555: snapshot too old: rollback segment number  with name "" too small

根据经验可能是屏蔽了undo或者undo损坏,然后有事务可能需要读undo,无法读到对应记录,可能出现此错误,因为无trace文件,尝试推进scn解决.当然这个问题可以通过open时做10046然后深入分析也许可以找到原因.

open数据库成功
根据上面的分析,重启库,推进scn,resetlogs库解决问题

SVRMGR> shutdown immediate
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
SVRMGR> startup pfile='init.ora' mount;
ORACLE instance started.
Total System Global Area                        141826208 bytes
Fixed Size                                          47264 bytes
Variable Size                                   124829696 bytes
Database Buffers                                 16777216 bytes
Redo Buffers                                       172032 bytes
Database mounted.
SVRMGR> alter database open ;
alter database open 
*
ORA-00600: internal error code, arguments: [3668], [1], [2], [55994], [55994], [4], [], []
SVRMGR> recover database using backup controlfile until cancel;
ORA-00279: change 613561560 generated at 07/30/12 09:17:11 needed for thread 1
ORA-00289: suggestion : /oracle/product/8.0.5/dbs/arch1_1.dbf
ORA-00280: change 613561560 for thread 1 is in sequence #1
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
Media recovery cancelled.
SVRMGR> alter database open resetlogs;
Statement processed.

这次恢复比较幸运,在备份到磁带过程中被覆盖的一个同名的数据文件,因为是index,通过查询dba_extents,然后删除并重建相关index,s数据库算恢复完全.有些时候,对数据库多一份备份,可能成为最后的救命稻草,哪怕是一份不是十分完整的备份.再次重复:对dba而言,数据库备份重于一切