Oracle的DBV工具

DBV(DBVERIFY)是Oracle提供的一个命令行工具，它可以对数据文件物理和逻辑两种一致性检查。但是这个工具不会检查索引记录和数据记录的匹配关系，这种检查必须使用analyze validate structure命令。

这个工具有如下特点：

• 以只读的方式打开数据文件，在检查过程中不会修改数据文件的内容。

• 可以在线检查数据文件，而不需要关闭数据库。

• 不能检查控制文件和日志文件，只能检查数据文件。

• 这个工具可以检查ASM文件，但数据库必须Open状态，并且需要通过USERID指定用户，比如：dbv file=+DG1/ORCL/datafile/system01.dbf userid=system/sys
  

• 在许多UNIX平台下，DBV要求数据文件有扩展名，如果没有可以通过建立链接的方法，然后对链接的方法，然后对链接文件进行操作，比如：ls -n /dev/rdsk/mydevice /tmp/mydevice.dbf

• 某些平台，DBV工具不能检查超过2GB的文件，如果碰到DBV-100错误，请先检查文件大小，MOS Bug 710888对这个问题有描述。

• DBV只会检查数据块的正确性，但不会关系数据块是否属于哪个对象。

• 对于祼设备建议指定END参数，避免超出数据文件范围。比如：dbv FILE=/dev/rdsk/r1.dbf END=。可以在v$datafile视图中用bytes字段除以块大小来获得END值。

使用示例：

[oracle@rhel6 ~]$ dbv file=/u01/app/oracle/oradata/test/users01.dbfDBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 16:42:26 2017Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbfDBVERIFY - Verification completeTotal Pages Examined         : 155520Total Pages Processed (Data) : 144530Total Pages Failing   (Data) : 0Total Pages Processed (Index): 52Total Pages Failing   (Index): 0Total Pages Processed (Other): 1248Total Pages Processed (Seg)  : 0Total Pages Failing   (Seg)  : 0Total Pages Empty            : 9690Total Pages Marked Corrupt   : 0Total Pages Influx           : 0Total Pages Encrypted        : 0Highest block SCN            : 3559792 (0.3559792)

这个工具报告使用的是page作为单位，含义和data block相同。从上面的检查结果Total Pages Marked Corrupt : 0可以看出文件没有坏块。

除了检查数据文件，这个工具还允许检查单独的Segment，这时参数值的格式为

查看对象的tsn,segfile,segblock属性：

zx@TEST>select t.ts#,s.header_file,s.header_block  2  from v$tablespace t,dba_segments s  3  where s.segment_name='T'  4  and t.name=s.tablespace_name;       TS# HEADER_FILE HEADER_BLOCK---------- ----------- ------------         4           4        45834

从上面的查询结果可行参数值为4.4.45834。检查Segment：

[oracle@rhel6 ~]$ dbv userid=system/123456 segment_id=4.4.45834DBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 20:58:33 2017Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.DBVERIFY - Verification starting : SEGMENT_ID = 4.4.45834DBVERIFY - Verification completeTotal Pages Examined         : 8Total Pages Processed (Data) : 5Total Pages Failing   (Data) : 0Total Pages Processed (Index): 0Total Pages Failing   (Index): 0Total Pages Processed (Other): 2Total Pages Processed (Seg)  : 1Total Pages Failing   (Seg)  : 0Total Pages Empty            : 0Total Pages Marked Corrupt   : 0Total Pages Influx           : 0Total Pages Encrypted        : 0Highest block SCN            : 3518579 (0.3518579)

下面人为创造一个坏块，用dbv来检查。

创建一个测试表

zx@TEST>create table bbed (id number,name varchar2(20)) tablespace users;Table created.zx@TEST>insert into bbed values(1,'zhaoxu');1 row created.zx@TEST>commit;Commit complete.

当前数据文件没有坏块

[oracle@rhel6 ~]$ dbv file=/u01/app/oracle/oradata/test/users01.dbfDBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 21:03:40 2017Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbfDBVERIFY - Verification completeTotal Pages Examined         : 155520Total Pages Processed (Data) : 66397Total Pages Failing   (Data) : 0Total Pages Processed (Index): 52Total Pages Failing   (Index): 0Total Pages Processed (Other): 88898Total Pages Processed (Seg)  : 0Total Pages Failing   (Seg)  : 0Total Pages Empty            : 173Total Pages Marked Corrupt   : 0Total Pages Influx           : 0Total Pages Encrypted        : 0Highest block SCN            : 3764775 (0.3764775)

获取表在文件中的存储信息

zx@TEST>set serveroutput onzx@TEST>declare rfno number;  2  rtype number;  3  ono number;  4  blkno number;  5  rowno number;  6  rid varchar2(30);  7  begin  8  select rowid into rid from bbed;  9  dbms_rowid.rowid_info(ROWID_IN=>rid,RELATIVE_FNO=>rfno,BLOCK_NUMBER=>blkno,ROW_NUMBER=>rowno,ROWID_TYPE=>rtype,OBJECT_NUMBER=>ono); 10  dbms_output.put_line(rfno||','||blkno||','||rowno); 11  end; 12  /4,45844,0PL/SQL procedure successfully completed.

使用bbed修改块信息

[oracle@rhel6 bbed]$ bbed parfile=bbed.parPassword: BBED: Release 2.0.0.0.0 - Limited Production on Mon May 22 21:17:18 2017Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.************* !!! For Oracle Internal Use only !!! ***************BBED> set dba 4,45844        DBA             0x0100b314 (16823060 4,45844)BBED> find /c zhaoxu File: /u01/app/oracle/oradata/test/users01.dbf (4) Block: 45844            Offsets: 8182 to 8191           Dba:0x0100b314------------------------------------------------------------------------ 7a68616f 78750106 5873  <32 bytes per line>BBED> dump /v dba 4,45844 offset 8182 count 32 File: /u01/app/oracle/oradata/test/users01.dbf (4) Block: 45844   Offsets: 8182 to 8191  Dba:0x0100b314------------------------------------------------------- 7a68616f 78750106 5873              l zhaoxu..Xs <16 bytes per line>BBED> modify 100 dba 4,45844Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y File: /u01/app/oracle/oradata/test/users01.dbf (4) Block: 45844            Offsets: 8182 to 8191           Dba:0x0100b314------------------------------------------------------------------------ 6468616f 78750106 5873  <32 bytes per line>BBED> dump /v dba 4,45844 offset 8182 count 32 File: /u01/app/oracle/oradata/test/users01.dbf (4) Block: 45844   Offsets: 8182 to 8191  Dba:0x0100b314------------------------------------------------------- 6468616f 78750106 5873              l dhaoxu..Xs <16 bytes per line>BBED> exit

再次使用dbv检查文件

[oracle@rhel6 bbed]$ dbv file=/u01/app/oracle/oradata/test/users01.dbfDBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 21:18:46 2017Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbfPage 45844 is marked corruptCorrupt block relative dba: 0x0100b314 (file 4, block 45844)Bad check value found during dbv: Data in bad block: type: 6 format: 2 rdba: 0x0100b314 last change scn: 0x0000.00397358 seq: 0x1 flg: 0x04 spare1: 0x0 spare2: 0x0 spare3: 0x0 consistency value in tail: 0x73580601 check value in block header: 0x7c2d computed block checksum: 0x1eDBVERIFY - Verification completeTotal Pages Examined         : 155520Total Pages Processed (Data) : 66396Total Pages Failing   (Data) : 0Total Pages Processed (Index): 52Total Pages Failing   (Index): 0Total Pages Processed (Other): 88898Total Pages Processed (Seg)  : 0Total Pages Failing   (Seg)  : 0Total Pages Empty            : 173Total Pages Marked Corrupt   : 1Total Pages Influx           : 0Total Pages Encrypted        : 0Highest block SCN            : 3764775 (0.3764775)

报告一个坏块，Total Pages Marked Corrupt : 1
再次查询测试表：

sys@TEST>select * from zx.bbed;        ID NAME---------- ------------------------------------------------------------         1 zhaoxu

查询正常，因为在buffer_cache中缓存了块，而修改的是文件中的块。两个块现在不一致，清空buffer cache后再次查询测试表。

zx@TEST>alter system  flush buffer_cache;System altered.zx@TEST>select * from bbed;select * from bbed              *ERROR at line 1:ORA-01578: ORACLE data block corrupted (file # 4, block # 45844)ORA-01110: data file 4: '/u01/app/oracle/oradata/test/users01.dbf'

查询报出错误ORA-01578。

使用dbv检查ASM文件中的数据文件，需要指定userid参数

[oracle@rac1 ~]$ dbv file=+DATA/orcl/datafile/users.259.925306091 userid=sys/123456DBVERIFY: Release 11.2.0.4.0 - Production on Mon May 22 16:48:22 2017Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.DBVERIFY - Verification starting : FILE = +DATA/orcl/datafile/users.259.925306091DBVERIFY - Verification completeTotal Pages Examined         : 640Total Pages Processed (Data) : 16Total Pages Failing   (Data) : 0Total Pages Processed (Index): 2Total Pages Failing   (Index): 0Total Pages Processed (Other): 593Total Pages Processed (Seg)  : 0Total Pages Failing   (Seg)  : 0Total Pages Empty            : 29Total Pages Marked Corrupt   : 0Total Pages Influx           : 0Total Pages Encrypted        : 0Highest block SCN            : 0 (0.0)

参考：《大话Oracle RAC》

MOS文档：文档 ID 35512.1