跳过rman坏块恢复

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标题：跳过rman坏块恢复

作者：惜分飞©版权所有[未经本人同意,不得以任何形式转载,否则有进一步追究法律责任的权利.]

在有些情况下,我们仅有一份rman备份,而这个时候rman 备份有出现坏块,使得我们的还原/恢复工作无法继续下去,导致数据大量丢失.我们可以通过设置event 19548/19549来跳过坏块,最大程度抢救数据
rman备份数据文件

C:\Users\XIFENFEI>rman target /
Recovery Manager: Release 11.2.0.3.0 - Production on Thu Jun 6 20:31:19 2013
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
connected to target database: XIFENFEI (DBID=1422012639)
RMAN> backup tablespace users format 'f:/users_bak.rman';
Starting backup at 06-JUN-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=197 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00004 name=E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF
channel ORA_DISK_1: starting piece 1 at 06-JUN-13
channel ORA_DISK_1: finished piece 1 at 06-JUN-13
piece handle=F:\USERS_BAK.RMAN tag=TAG20130606T203154 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03
Finished backup at 06-JUN-13

切换归档日志

SQL> alter system switch logfile;
System altered.
SQL> /
System altered.
SQL> /
System altered.
SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            E:\oracle\product\11.2.0\dbhome_1\RDBMS
Oldest online log sequence     95
Next log sequence to archive   97
Current log sequence           97

重命名数据文件

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
--------------------------------------
e:\oracle\oradata\XIFENFEI>move USERS01.DBF USERS01_bak.DBF
移动了         1 个文件。
--------------------------------------
SQL> startup
ORACLE instance started.
Total System Global Area  418484224 bytes
Fixed Size                  1385052 bytes
Variable Size             327159204 bytes
Database Buffers           83886080 bytes
Redo Buffers                6053888 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4: 'E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF'

破坏备份集
破坏前

破坏后

这里很明显,我通过ue把rman备份集中的T修改为了A,肯定破坏了文件,使之出现坏块

rman还原数据文件

C:\Users\XIFENFEI>rman target /
Recovery Manager: Release 11.2.0.3.0 - Production on Thu Jun 6 21:02:41 2013
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
connected to target database: XIFENFEI (DBID=1422012639, not open)
RMAN> restore datafile 4;
Starting restore at 06-JUN-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=63 device type=DISK
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00004 to E:\ORACLE\ORADATA\XIFENFEI\USERS
01.DBF
channel ORA_DISK_1: reading from backup piece F:\USERS_BAK.RMAN
channel ORA_DISK_1: ORA-19870: error while restoring backup piece F:\USERS_BAK.R
MAN
ORA-19612: datafile 4 not restored due to missing or corrupt data
failover to previous backup
creating datafile file number=4 name=E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF
Finished restore at 06-JUN-13

这里可以清晰的看到rman报ORA-19612错误，restore 失败,alert日志为:

Thu Jun 06 21:02:31 2013
ALTER DATABASE OPEN
Errors in file E:\ORACLE\diag\rdbms\xifenfei\xff\trace\xff_dbw0_7400.trc:
ORA-01157: ????/?????? 4 - ??? DBWR ????
ORA-01110: ???? 4: 'E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF'
ORA-27041: ??????
OSD-04002: unable to open file
O/S-Error: (OS 2) 系统找不到指定的文件。
Errors in file E:\ORACLE\diag\rdbms\xifenfei\xff\trace\xff_ora_4272.trc:
ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4: 'E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF'
ORA-1157 signalled during: ALTER DATABASE OPEN...
Thu Jun 06 21:02:33 2013
Checker run found 1 new persistent data failures
Thu Jun 06 21:03:23 2013
Corrupt block 101 found during reading backup piece, file=F:\USERS_BAK.RMAN, corr_type=3
Reread of blocknum=101, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=101, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=101, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=101, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=101, file=F:\USERS_BAK.RMAN, found same corrupt data
Continuing reading piece F:\USERS_BAK.RMAN, no other copies available.

rman备份集有坏块，导致rman还原无法正常进行下去,还原后的数据文件大小

观察已经正常还原出来数据文件情况

SQL> select CHECKPOINT_CHANGE#,file# from v$datafile_header;
CHECKPOINT_CHANGE#      FILE#
------------------ ----------
           1571582          1
           1571582          2
           1571582          3
             18379          4
           1571582          5
           1571582          6
           1571582          7
SQL> recover database datafile 4 ;
ORA-00274: illegal recovery option DATAFILE
SQL> recover datafile 4;
ORA-00279: change 18379 generated at 01/20/2013 17:13:56 needed for thread 1
ORA-00289: suggestion :
E:\ORACLE\PRODUCT\11.2.0\DBHOME_1\RDBMS\ARC0000000001_0805223583.0001
ORA-00280: change 18379 for thread 1 is in sequence #1
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

rman只是还原了很小的一部分文件,做恢复提示需要从归档日志seq 1开始(某些情况可能需要其他归档,总之不是正常情况),证明rman还原异常

设置event事件还原

SQL> shutdown abort;
ORACLE instance shut down.
SQL> startup pfile='e:/pfile.txt' mount;
ORACLE instance started.
Total System Global Area  418484224 bytes
Fixed Size                  1385052 bytes
Variable Size             327159204 bytes
Database Buffers           83886080 bytes
Redo Buffers                6053888 bytes
Database mounted.
SQL> show parameter event;
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
event                                string      19548 trace name context forev
                                                 er, 19549 trace name context f
                                                 orever

Event 19548:This will attempt to restore content of the corrupted block if it is possible.
Event 19549:This will suppress erroring out during restore

rman还原数据文件

RMAN> restore datafile 4;
Starting restore at 06-JUN-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=63 device type=DISK
channel ORA_DISK_1: starting datafile backup set restore
channel ORA_DISK_1: specifying datafile(s) to restore from backup set
channel ORA_DISK_1: restoring datafile 00004 to E:\ORACLE\ORADATA\XIFENFEI\USERS
01.DBF
channel ORA_DISK_1: reading from backup piece F:\USERS_BAK.RMAN
channel ORA_DISK_1: piece handle=F:\USERS_BAK.RMAN tag=TAG20130606T203154
channel ORA_DISK_1: restored backup piece 1
channel ORA_DISK_1: restore complete, elapsed time: 00:00:35
Finished restore at 06-JUN-13

这里证明数据库rman有坏块通过rman还原成功,alert日志提示如下

Thu Jun 06 21:29:53 2013
WARNING: The block that appears to be block number 100
         in file 4 is corrupt in backup piece F:\USERS_BAK.RMAN.
         Such blocks would usually be formatted as empty
         in the restored file, but event 19548 has been
         set to include the block as-is in the restored
         file.
Corrupt block 102 found during reading backup piece, file=F:\USERS_BAK.RMAN, corr_type=-2
Reread of blocknum=102, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=102, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=102, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=102, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=102, file=F:\USERS_BAK.RMAN, found same corrupt data
Continuing reading piece F:\USERS_BAK.RMAN, no other copies available.
…………
Corrupt block 258 found during reading backup piece, file=F:\USERS_BAK.RMAN, corr_type=-2
Reread of blocknum=258, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=258, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=258, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=258, file=F:\USERS_BAK.RMAN, found same corrupt data
Reread of blocknum=258, file=F:\USERS_BAK.RMAN, found same corrupt data
Continuing reading piece F:\USERS_BAK.RMAN, no other copies available.
WARNING: some data in the backup of file 4 was missing
         or corrupt.  Event 19549 has been set to allow
         the file to be restored anyway.
           backup header block count: 5369
           backup actual block count: 5212
              backup header checksum: -218250743
              backup actual checksum: 1442665538
Full restore complete of datafile 4 E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF.  Elapsed time: 0:00:25
  checkpoint is 1570136
  last deallocation scn is 1508457

这里rman还原依然遇到很多坏块,但是均跳过坏块,还是完整的恢复出来的数据文件(大小)

rman还原数据文件

RMAN> recover datafile 4;
Starting recover at 06-JUN-13
using channel ORA_DISK_1
starting media recovery
archived log for thread 1 with sequence 94 is already on disk as file E:\ORACLE\
PRODUCT\11.2.0\DBHOME_1\RDBMS\ARC0000000094_0805223583.0001
archived log for thread 1 with sequence 95 is already on disk as file E:\ORACLE\
PRODUCT\11.2.0\DBHOME_1\RDBMS\ARC0000000095_0805223583.0001
archived log for thread 1 with sequence 96 is already on disk as file E:\ORACLE\
PRODUCT\11.2.0\DBHOME_1\RDBMS\ARC0000000096_0805223583.0001
archived log file name=E:\ORACLE\PRODUCT\11.2.0\DBHOME_1\RDBMS\ARC0000000094_080
5223583.0001 thread=1 sequence=94
media recovery complete, elapsed time: 00:00:00
Finished recover at 06-JUN-13

这里可以明显的看到在recover过程中数据库应用的是备份后的所有归档,数据文件是正常被还原出来(坏块除外)

查询对象

SQL> alter database open;
Database altered.
SQL> conn test/test
Connected.
SQL> select * from tab;
TNAME                          TABTYPE  CLUSTERID
------------------------------ ------- ----------
STB101                         TABLE
SQL> select count(*) from stb101;
select count(*) from stb101
                     *
ERROR at line 1:
ORA-08103: object no longer exists

dbv检查坏块

e:\oracle\oradata\XIFENFEI>dbv file=USERS01.DBF
DBVERIFY: Release 11.2.0.3.0 - Production on Thu Jun 6 23:59:49 2013
Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.
DBVERIFY - Verification starting : FILE = E:\ORACLE\ORADATA\XIFENFEI\USERS01.DBF
Page 100 is marked corrupt
Corrupt block relative dba: 0x01000064 (file 4, block 100)
Bad check value found during dbv:
Data in bad block:
 type: 30 format: 2 rdba: 0x01000064
 last change scn: 0x0000.00004890 seq: 0x1 flg: 0x04
 spare1: 0x0 spare2: 0x0 spare3: 0x0
 consistency value in tail: 0x48901e01
 check value in block header: 0x8311
 computed block checksum: 0x20
DBVERIFY - Verification complete
Total Pages Examined         : 12320
Total Pages Processed (Data) : 4952
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 7069
Total Pages Processed (Seg)  : 0
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 298

证明设置了event之后，rman确实跳过了备份集中的坏块,而且是直接还原了坏块内容,证明了event 19548和19549作用

补充说明
在非特殊情况下强烈不建议设置相关event跳过rman中的坏块来还原/恢复数据库,这样将对数据的丢失,甚至数据库是否可以正常open不好评估,rman备份重要,确保rman备份可用也很重要.

One thought on “跳过rman坏块恢复”

  1. 补充说明:

    Bug 2973616 warns the usage of 19548 which can have some dangerous side effects.
Hence the suggestion is to use 19549 by which we will lose the data from the corrupt blocks.
The above fix is introduced with Bug 2973616 in following versions
8.1.7.5.0 (not to be released)
9.2.0.4.0
10.1.0.0.0
In 8.1.7.4, we have a one-off patch on Solaris (64 bits) that introduces this fix.
For other platforms you need to search in metalink for Bug 2973616.
    回复

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