Oracle壞塊處理

oracle 壞塊問題處理

1、說明

壞塊問題是經常出現在數據庫系統中的，如果沒有合適的處理方法往往會導致壞塊對象不可用或者數據丟失。本文從壞塊產生開始說起，著重說明一但壞塊產生后不同情況的處理方法。

2、壞塊產生的原因：

硬件的I/O錯誤
操作系統的I/O錯誤或緩沖問題
內存或paging問題
磁盤修復工具
一個數據文件的一部分正在被覆蓋
Oracle試圖訪問一個未被格式化的系統塊失敗
數據文件部分溢出
Oracle或者操作系統的bug

3、壞塊的發現：

3.1、Alter日志報錯

Tue Aug 17 10:48:07 2010

Corrupt Block Found

TSN = 7, TSNAME = BTEST

RFN 6, BLK = 839, rdba = 25166663

OBJN = 49205, BJD = 49205, BJECT= BOBJ, SUBOBJECT =

Segment wner= AN, Segment Type = Table Segment

其中RFN表示的是relative_fno，6號文件的839塊，段類型為表段，是表bobj出現壞塊。

3.2、查詢報錯

SQL> select count(*) from bobj;

select count(*) from bobj

*

ERROR at line 1:

ORA-01578: ORACLE data block corrupted (file # 6, block # 839)

ORA-01110: data file 6: 'F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\BTEST.DBF'

3.3、分析表報錯

SQL> analyze table bobj validate structure cascade;

analyze table bobj validate structure cascade

*

ERROR at line 1:

ORA-01578: ORACLE data block corrupted (file # 6, block # 839)

ORA-01110: data file 6: 'F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\BTEST.DBF'

3.4、Rman備份報錯

RMAN> backup tablespace btest;

Starting backup at 17-8月 -10

using channel ORA_DISK_1

channel ORA_DISK_1: starting full datafile backupset

channel ORA_DISK_1: specifying datafile(s) in backupset

input datafile fno=00006 name=F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\BTEST.DBF

channel ORA_DISK_1: starting piece 1 at 17-8月 -10

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03009: failure of backup command on ORA_DISK_1 channel at 08/17/2010 11:03:09

ORA-19566: exceeded limit of 0 corrupt blocks for file F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\BTEST.DBF

3.5、Dbv檢查報錯

F:\oracle\product\10.1.0\oradata\db10>dbv file=BTEST.DBF blocksize=8192

DBVERIFY: Release 10.1.0.2.0 - Production on 星期二 8月 17 10:49:02 2010

Copyright (c) 1982, 2004, Oracle. All rights reserved.

DBVERIFY - Verification starting : FILE = BTEST.DBF

Page 839 is marked corrupt

Corrupt block relative dba: 0x01800347 (file 6, block 839)

Bad check value found during dbv:

Data in bad block:

type: 6 format: 2 rdba: 0x01800347

last change scn: 0x0000.0005246f seq: 0x1 flg: 0x04

spare1: 0x0 spare2: 0x0 spare3: 0x0

consistency value in tail: 0x246f0601

check value in block header: 0x50c2

computed block checksum: 0x2751

DBVERIFY - Verification complete

Total Pages Examined : 5376

Total Pages Processed (Data) : 5165

Total Pages Failing (Data) : 0

Total Pages Processed (Index): 0

Total Pages Failing (Index): 0

Total Pages Processed (Other): 9

Total Pages Processed (Seg) : 0

Total Pages Failing (Seg) : 0

Total Pages Empty : 201

Total Pages Marked Corrupt : 1

Total Pages Influx : 0

3.6、查詢壞塊發生的數據文件以及對應表空間

Select file_name,tablespace_name,file_id “AFN”,relative_fno “RFN”
From dba_data_files;
Select file_name,tablespace_name,file_id, relative_fno“RFN”
From dba_temp_files;
　　

3.7、查詢存在壞塊的對象是什么：

SELECT tablespace_name, segment_type, owner,

segment_name, partition_name FROM

dba_extents WHERE file_id =v_file_id and v_block_id

between block_id AND block_id + blocks – 1；

4、出現壞塊的常見對象：

Sys用戶下的對象
　　回滾段
　　臨時段
　　索引或者分區索引

表

5、問題的處理

5.1、無備份情況下的恢復

5.1.1、Sys用戶下的對象，需要謹慎處理。

5.1.2、回滾段壞塊采用類似ora-600（4000）的處理方法將回滾段刪除即可。會造成事物失敗，數據丟失。

5.1.3、索引：重建，期間會鎖表對業務有影響，數據不會丟失。

5.1.4、表：

5.1.4．1、EVENT10231

SQL> select count(*)from bobj;

COUNT(*)

----------

376240

SQL> analyze table bobj validate structure cascade;

analyze table bobj validate structure cascade

*

ERROR at line 1:

ORA-01578: ORACLE data block corrupted (file # 6, block # 495)

ORA-01110: data file 6: 'F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\BTEST.DBF'

SQL> alter session set events ='10231 trace name context forever,level 10';

Session altered.

SQL> select count(*) from bobj;

COUNT(*)

----------

376169

忽略了壞塊進行讀寫，所以數據量上有變化，丟失了一部分數據。

5.1.4．2、ROWID RANGE SCAN

FUNCTION ROWID_CREATE RETURNS ROWID

Argument Name Type In/Out Default?

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

ROWID_TYPE NUMBER IN

OBJECT_NUMBER NUMBER IN

RELATIVE_FNO NUMBER IN

BLOCK_NUMBER NUMBER IN

ROW_NUMBER NUMBER IN

SQL> select * from v$database_block_corruption;

FILE# BLOCK# BLOCKS CORRUPTION_CHANGE# CORRUPTIO

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

6 839 1 0 CHECKSUM

SQL> SELECT dbms_rowid.rowid_create(1,49205,6,839,0) from DUAL;

DBMS_ROWID.ROWID_C

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

AAAMA1AAGAAAANHAAA

SQL> SELECT dbms_rowid.rowid_create(1,49205,6,840,0) from DUAL;

DBMS_ROWID.ROWID_C

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

AAAMA1AAGAAAANIAAA

SQL> create table bbobj tablespace btest as select * from bobj where 1=2;

Table created.

SQL> insert into bbobj select /*+ rowid(a) */ * from bobj where rowid<'AAAMA1AAG

AAAANHAAA';

60993 rows created.

SQL> insert into bbobj select /*+ rowid(a) */ * from bobj where rowid>='AAAMA1AAG

AAAANIAAA';

315108 rows created.

SQL> commit;

Commit complete.

SQL> select count(*) from bbobj;

COUNT(*)

----------

376101

從v$database_block_corruption中可以查處當前數據庫中的壞塊信息

通過調用dbms_rowid.rowid_create確認出壞塊對應的rowid，重新創建表結構相同的表，并以rowid為條件跳過壞塊將好數據存入到中間表中，損失一部分數據，仍然可以將壞塊的影響忽略掉。

5.1.4.3、Dbms_repair

以sys用戶執行

PROCEDURE SKIP_CORRUPT_BLOCKS

Argument Name Type In/Out Default?

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

SCHEMA_NAME VARCHAR2 IN

OBJECT_NAME VARCHAR2 IN

OBJECT_TYPE BINARY_INTEGER IN DEFAULT

FLAGS BINARY_INTEGER IN DEFAULT

SQL> Execute DBMS_REPAIR.SKIP_CORRUPT_BLOCKS('AN','BOBJ')

PL/SQL procedure successfully completed.

SQL> conn an/an

Connected.

SQL> select count(*) from bobj;

COUNT(*)

----------

376169

試用sys用戶調用dbms_repair中的skip_corrupt_blocks忽略對象中的壞塊，同樣會丟失壞塊中的數據。包中還包含過程FIX_CORRUPT_BLOCKS，可以fix掉壞塊。

5.2、有備份情況下的恢復

5.2.1、Blockrecover

RMAN> blockrecover datafile 5 block 425;

Starting blockrecover at 17-8月 -10

using channel ORA_DISK_1

channel ORA_DISK_1: restoring block(s)

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

restoring blocks of datafile 00005

channel ORA_DISK_1: restored block(s) from backup piece 1

piece handle=F:\ORACLE\PRODUCT\10.1.0\FLASH_RECOVERY_AREA\DB10\BACKUPSET\2010_08_17\O1_MF_NNNDF_TAG20100817T162508_66NKV5B8_.BKP tag=TAG20100817T162508

channel ORA_DISK_1: block restore complete

starting media recovery

media recovery complete

Finished blockrecover at 17-8月 -10

SQL> select count(*) from an.atest;

COUNT(*)

----------

376240

5.2.2、Recover datafile

SQL> select count(*) from an.atest;

select count(*) from an.atest

*

ERROR at line 1:

ORA-01578: ORACLE data block corrupted (file # 5, block # 963)

ORA-01110: data file 5: 'F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\ATEST.DBF'

RMAN> sql " alter database datafile 5 offline";

sql statement: alter database datafile 5 offline

RMAN> restore datafile 5;

Starting restore at 17-8月 -10

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 00005 to F:\ORACLE\PRODUCT\10.1.0\ORADATA\DB10\ATEST.DBF

channel ORA_DISK_1: restored backup piece 1

piece handle=F:\ORACLE\PRODUCT\10.1.0\FLASH_RECOVERY_AREA\DB10\BACKUPSET\2010_08_17\O1_MF_NNNDF_TAG20100817T162508_66NKV5B8_.BKP tag=TAG20100817T162508

channel ORA_DISK_1: restore complete

Finished restore at 17-8月 -10

RMAN> recover datafile 5;

Starting recover at 17-8月 -10

using channel ORA_DISK_1

starting media recovery

media recovery complete

Finished recover at 17-8月 -10

RMAN> sql " alter database datafile 5 online";

sql statement: alter database datafile 5 online

SQL> select count(*) from an.atest;

COUNT(*)

----------

376240

5.3、Rman備份跳過壞塊

SET MAXCORRUPT FOR DATAFILE filename TO n；

例：

run {

allocate channel node1 type disk;

SET MAXCORRUPT FOR DATAFILE 8 TO 3；

set limit channel node1 kbytes = 1800000;

backup as compressed backupset full database format '$BACKUPDIR/full_%d_%T_%s_%p' plus archivelog format '$BACKUPDIR/arch_%d_%T_%s_%p' delete all input;

backup current controlfile format '$BACKUPDIR/ctl_%d_%T_%s_%p' TAG "control.bak";

release channel node1;

}