DBV(DBVERIFY)是Oracle提供的一個命令行工具，它可以對數據文件物理和邏輯兩種一致性檢查。但是這個工具不會檢查索引記錄和數據記錄的匹配關系，這種檢查必須使用analyze validate structure命令。
這個工具有如下特點：
以只讀的方式打開數據文件，在檢查過程中不會修改數據文件的內容。
可以在線檢查數據文件，而不需要關閉數據庫。
不能檢查控制文件和日志文件，只能檢查數據文件。
這個工具可以檢查ASM文件，但數據庫必須Open狀態，并且需要通過USERID指定用戶，比如：dbv file=+DG1/ORCL/datafile/system01.dbf userid=system/sys
在許多UNIX平臺下，DBV要求數據文件有擴展名，如果沒有可以通過建立鏈接的方法，然后對鏈接的方法，然后對鏈接文件進行操作，比如：ls -n /dev/rdsk/mydevice /tmp/mydevice.dbf
某些平臺，DBV工具不能檢查超過2GB的文件，如果碰到DBV-100錯誤，請先檢查文件大小，MOS Bug 710888對這個問題有描述。
DBV只會檢查數據塊的正確性，但不會關系數據塊是否屬于哪個對象。
對于祼設備建議指定END參數，避免超出數據文件范圍。比如：dbv FILE=/dev/rdsk/r1.dbf END=<last_block_number>?？梢栽趘$datafile視圖中用bytes字段除以塊大小來獲得END值。
| 參數 | 含義 | 缺省值 |
| FILE | 要檢查的數據文件名 | 沒有缺省值 |
| START | 檢查起始數據塊號 | 數據文件的第一個數據塊 |
| END | 檢查的最后一個數據塊號 | 數據文件的最后一個數據塊 |
| BLOCKSIZE | 數據塊大小，這個值要和數據庫的DB_BLOCK_SIZE參數值一致 | 缺省值8192 |
| LOGFILE | 檢查結果日志文件 | 沒有缺省值 |
| FEEDBAK | 顯示進度 | 0 |
| PARFILE | 參數文件名 | 沒有缺省值 |
| USERID | 用戶名、密碼 | 沒有缺省值 |
| SEGMENT_ID | 段ID，參數格式<tsn.segfile.segblock> | 沒有缺省值 |
使用示例：
[oracle@rhel6 ~]$ dbv file=/u01/app/oracle/oradata/test/users01.dbf DBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 16:42:26 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbf DBVERIFY - Verification complete Total Pages Examined : 155520 Total Pages Processed (Data) : 144530 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 52 Total Pages Failing (Index): 0 Total Pages Processed (Other): 1248 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 9690 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 3559792 (0.3559792)
這個工具報告使用的是page作為單位，含義和data block相同。從上面的檢查結果Total Pages Marked Corrupt : 0可以看出文件沒有壞塊。
除了檢查數據文件，這個工具還允許檢查單獨的Segment，這時參數值的格式為<tsn.segfile.segblock>
查看對象的tsn,segfile,segblock屬性：
zx@TEST>select t.ts#,s.header_file,s.header_block 2 from v$tablespace t,dba_segments s 3 where s.segment_name='T' 4 and t.name=s.tablespace_name; TS# HEADER_FILE HEADER_BLOCK ---------- ----------- ------------ 4 4 45834
從上面的查詢結果可行參數值為4.4.45834。檢查Segment：
[oracle@rhel6 ~]$ dbv userid=system/123456 segment_id=4.4.45834 DBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 20:58:33 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : SEGMENT_ID = 4.4.45834 DBVERIFY - Verification complete Total Pages Examined : 8 Total Pages Processed (Data) : 5 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 0 Total Pages Failing (Index): 0 Total Pages Processed (Other): 2 Total Pages Processed (Seg) : 1 Total Pages Failing (Seg) : 0 Total Pages Empty : 0 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 3518579 (0.3518579)
下面人為創造一個壞塊，用dbv來檢查。
創建一個測試表
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.
當前數據文件沒有壞塊
[oracle@rhel6 ~]$ dbv file=/u01/app/oracle/oradata/test/users01.dbf DBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 21:03:40 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbf DBVERIFY - Verification complete Total Pages Examined : 155520 Total Pages Processed (Data) : 66397 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 52 Total Pages Failing (Index): 0 Total Pages Processed (Other): 88898 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 173 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 3764775 (0.3764775)
獲取表在文件中的存儲信息
zx@TEST>set serveroutput on zx@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 / 4,45844,0 PL/SQL procedure successfully completed.
使用bbed修改塊信息
[oracle@rhel6 bbed]$ bbed parfile=bbed.par Password: BBED: Release 2.0.0.0.0 - Limited Production on Mon May 22 21:17:18 2017 Copyright (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 4,45844 Warning: 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檢查文件
[oracle@rhel6 bbed]$ dbv file=/u01/app/oracle/oradata/test/users01.dbf DBVERIFY: Release 11.2.0.1.0 - Production on Mon May 22 21:18:46 2017 Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/test/users01.dbf Page 45844 is marked corrupt Corrupt 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: 0x1e DBVERIFY - Verification complete Total Pages Examined : 155520 Total Pages Processed (Data) : 66396 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 52 Total Pages Failing (Index): 0 Total Pages Processed (Other): 88898 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 173 Total Pages Marked Corrupt : 1 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 3764775 (0.3764775)
報告一個壞塊，Total Pages Marked Corrupt : 1
再次查詢測試表：
sys@TEST>select * from zx.bbed; ID NAME ---------- ------------------------------------------------------------ 1 zhaoxu
查詢正常，因為在buffer_cache中緩存了塊，而修改的是文件中的塊。兩個塊現在不一致，清空buffer cache后再次查詢測試表。
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'
查詢報出錯誤ORA-01578。
使用dbv檢查ASM文件中的數據文件，需要指定userid參數
[oracle@rac1 ~]$ dbv file=+DATA/orcl/datafile/users.259.925306091 userid=sys/123456 DBVERIFY: Release 11.2.0.4.0 - Production on Mon May 22 16:48:22 2017 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = +DATA/orcl/datafile/users.259.925306091 DBVERIFY - Verification complete Total Pages Examined : 640 Total Pages Processed (Data) : 16 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 2 Total Pages Failing (Index): 0 Total Pages Processed (Other): 593 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 29 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 0 (0.0)
參考：《大話Oracle RAC》
MOS文檔：文檔 ID 35512.1
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