乱用_allow_resetlogs_corruption参数导致悲剧

一个朋友11.2.0.1的数据库因为断电,出现不能正常open问题,自己尝试恢复,折腾了几天,最后让我帮忙的时候错误如下

SQL> startup
ORACLE 例程已经启动。

Total System Global Area  778387456 bytes
Fixed Size                  1374808 bytes
Variable Size             545260968 bytes
Database Buffers          226492416 bytes
Redo Buffers                5259264 bytes
数据库装载完毕。
ORA-01092: ORACLE instance terminated. Disconnection forced
ORA-00604: error occurred at recursive SQL level 1
ORA-01578: ORACLE data block corrupted (file # 1, block # 225)
ORA-01110: data file 1: 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'
进程 ID: 5964
会话 ID: 1144 序列号: 5

从启动的日志提示看初步判断就是悲剧了,因为根据经验值在11gr2版本中,该错误就是undo$(分析trace文件进步一确定是undo$),该block出现异常,数据库在启动的时候要扫描该表，把相关的回滚段给online起来,现在他异常了,数据库肯定无法正常启动
dbv检查数据库文件

F:\>dbv file='F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'

DBVERIFY: Release 11.2.0.1.0 - Production on 星期三 5月 22 11:06:00 2013

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

DBVERIFY - 开始验证: FILE = F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF
页 225 流入 - 很可能是介质损坏
Corrupt block relative dba: 0x004000e1 (file 1, block 225)
Fractured block found during dbv:
Data in bad block:
 type: 6 format: 2 rdba: 0x004000e1
 last change scn: 0x0000.00d65120 seq: 0x1 flg: 0x06
 spare1: 0x0 spare2: 0x0 spare3: 0x0
 consistency value in tail: 0xb98e0601
 check value in block header: 0xb307
 computed block checksum: 0xe8ae



DBVERIFY - 验证完成

检查的页总数: 134400
处理的页总数 (数据): 98226
失败的页总数 (数据): 0
处理的页总数 (索引): 14189
失败的页总数 (索引): 0
处理的页总数 (其他): 4178
处理的总页数 (段)  : 1
失败的总页数 (段)  : 0
空的页总数: 17806
标记为损坏的总页数: 1
流入的页总数: 1
加密的总页数        : 0
最高块 SCN            : 14045769 (0.14045769)

看到这里,可以确定坏块的存在，根据上面的提示,我们发现tailchk值不正确,应该是5120+06+01,而不该是b98e0601,通过bbed查看

BBED> p kcbh
struct kcbh, 20 bytes                       @0
   ub1 type_kcbh                            @0        0x06
   ub1 frmt_kcbh                            @1        0xa2
   ub1 spare1_kcbh                          @2        0x00
   ub1 spare2_kcbh                          @3        0x00
   ub4 rdba_kcbh                            @4        0x004000e1
   ub4 bas_kcbh                             @8        0x00d65120
   ub2 wrp_kcbh                             @12       0x0000
   ub1 seq_kcbh                             @14       0x01
   ub1 flg_kcbh                             @15       0x06 (KCBHFDLC, KCBHFCKV)
   ub2 chkval_kcbh                          @16       0x5ba9
   ub2 spare3_kcbh                          @18       0x0000

BBED> p tailchk
ub4 tailchk                                 @8188     0xb98e0601

进一步证明是tailchk异常导致,分析alert日志,数据库异常断电,然后启动的时候发现如下错误

Recovery of Online Redo Log: Thread 1 Group 2 Seq 431 Reading mem 0
  Mem# 0: F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\REDO02.LOG
RECOVERY OF THREAD 1 STUCK AT BLOCK 451 OF FILE 3
Aborting crash recovery due to error 1172
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_772.trc:
ORA-01172: 线程 1 的恢复停止在块 451 (在文件 3 中)
ORA-01151: 如果需要, 请使用介质恢复以恢复块和还原备份
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_772.trc:
ORA-01172: 线程 1 的恢复停止在块 451 (在文件 3 中)
ORA-01151: 如果需要, 请使用介质恢复以恢复块和还原备份
ORA-1172 signalled during: alter database open...
Tue May 21 14:27:29 2013
ALTER DATABASE RECOVER  datafile 3  
Media Recovery Start
Serial Media Recovery started
Recovery of Online Redo Log: Thread 1 Group 2 Seq 431 Reading mem 0
  Mem# 0: F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\REDO02.LOG
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_772.trc  (incident=112164):
ORA-00600: 内部错误代码, 参数: [3020], [3], [451], [12583363], [], [], [], [], [], [], [], []
ORA-10567: Redo is inconsistent with data block (file# 3, block# 451, file offset is 3694592 bytes)
ORA-10564: tablespace UNDOTBS1
ORA-01110: 数据文件 3: 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\UNDOTBS01.DBF'
ORA-10560: block type 'KTU UNDO BLOCK'
Media Recovery failed with error 600
ORA-283 signalled during: ALTER DATABASE RECOVER  datafile 3  ...

因为file# 3, block# 451和redo信息不一致,出现ora-600[3020]错误,而file# 3为undo文件,朋友从而设置undo_management=’manual’并设置了_allow_resetlogs_corruption=true,然后进行不完全恢复,从而出现了如下错误提示

Tue May 21 14:41:23 2013
SMON: enabling cache recovery
Corrupt block relative dba: 0x004000e1 (file 1, block 225)
Fractured block found during buffer read
Data in bad block:
 type: 6 format: 2 rdba: 0x004000e1
 last change scn: 0x0000.00d65120 seq: 0x1 flg: 0x06
 spare1: 0x0 spare2: 0x0 spare3: 0x0
 consistency value in tail: 0xb98e0601
 check value in block header: 0xb307
 computed block checksum: 0xe8ae
Reading datafile 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'
for corruption at rdba: 0x004000e1 (file 1, block 225)
Reread (file 1, block 225) found same corrupt data
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_4892.trc  (incident=120165):
ORA-01578: ORACLE 数据块损坏 (文件号 1, 块号 225)
ORA-01110: 数据文件 1: 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_4892.trc:
ORA-00604: 递归 SQL 级别 1 出现错误
ORA-01578: ORACLE 数据块损坏 (文件号 1, 块号 225)
ORA-01110: 数据文件 1: 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'
Errors in file f:\app\administrator\diag\rdbms\yfcloud\yfcloud\trace\yfcloud_ora_4892.trc:
ORA-00604: 递归 SQL 级别 1 出现错误
ORA-01578: ORACLE 数据块损坏 (文件号 1, 块号 225)
ORA-01110: 数据文件 1: 'F:\APP\ADMINISTRATOR\ORADATA\YFCLOUD\SYSTEM01.DBF'
Error 604 happened during db open, shutting down database
USER (ospid: 4892): terminating the instance due to error 604

从而的原因基本上可以从操作过程中了解到:数据库是因为file# 3 block# 451和redo不一致导致问题,而恢复的操作人员冲动的使用了_allow_resetlogs_corruption参数,从而使得数据库出现了不一致性,也就是导致file# 1 block# 225坏块的根本原因,针对这样的情况,完全没有到使用_allow_resetlogs_corruption隐含参数地步

使用bbed修改tailchk

BBED> p tailchk
ub4 tailchk                                 @8188     0xb98e0601

BBED> verify
DBVERIFY - Verification starting
FILE = system01.dbf
BLOCK = 225

Block 225 is corrupt
***
Corrupt block relative dba: 0x004000e1 (file 0, block 225)
Fractured block found during verification
Data in bad block -
 type: 6 format: 2 rdba: 0x004000e1
 last change scn: 0x0000.00d65120 seq: 0x1 flg: 0x06
 consistency value in tail: 0xb98e0601
 check value in block header: 0x5ba9, computed block checksum: 0x0
 spare1: 0x0, spare2: 0x0, spare3: 0x0
***


DBVERIFY - Verification complete

Total Blocks Examined         : 1
Total Blocks Processed (Data) : 0
Total Blocks Failing   (Data) : 0
Total Blocks Processed (Index): 0
Total Blocks Failing   (Index): 0
Total Blocks Empty            : 0
Total Blocks Marked Corrupt   : 1
Total Blocks Influx           : 2

BBED> m /x 01062051
 File: system01.dbf (0)
 Block: 226              Offsets: 8188 to 8191           Dba:0x00000000
------------------------------------------------------------------------
 01062051

 <32 bytes per line>

BBED> p tailchk
ub4 tailchk                                 @8188     0x51200601

BBED> sum apply
Check value for File 0, Block 226:
current = 0xb307, required = 0xb307

BBED> verify
DBVERIFY - Verification starting
FILE = system01.dbf
BLOCK = 225


DBVERIFY - Verification complete

Total Blocks Examined         : 1
Total Blocks Processed (Data) : 1
Total Blocks Failing   (Data) : 0
Total Blocks Processed (Index): 0
Total Blocks Failing   (Index): 0
Total Blocks Empty            : 0
Total Blocks Marked Corrupt   : 0
Total Blocks Influx           : 0

bbed修改block之后,数据库直接正常打开,完成数据库恢复任务,在这里很明显是因为错误的使用了_allow_resetlogs_corruption参数,屏蔽了redo前滚导致了相关的坏块,所以大家在数据库异常恢复的时候,需要知道各个参数的意义,而不要乱使用,很可能导致不可控结果