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數據文件頭中的scn要與控制文件中的scn一致,數據庫才可以open,在open過程中我們可以通過bbed來修改某個數據文件頭的scn,來欺騙oracle,來open庫。
1、環境如下
使用Oracle 11gR2進行測試,具體版本為11.2.0.4
SYS@xbtst SQL>select file#,name,checkpoint_change#,checkpoint_time from v$datafile; FILE# NAME CHECKPOINT_CHANGE# CHECKPOINT_TIME ---------- ---------------------------------------- ------------------ ------------------- 1 /dbdata/oradata/xbtst/system01.dbf 1233066 2016-11-10 11:23:44 2 /dbdata/oradata/xbtst/sysaux01.dbf 1233066 2016-11-10 11:23:44 3 /dbdata/oradata/xbtst/undotbs01.dbf 1233066 2016-11-10 11:23:44 4 /dbdata/oradata/xbtst/users01.dbf 1233066 2016-11-10 11:23:44 5 /dbdata/oradata/xbtst/moe01.dbf 1233066 2016-11-10 11:23:44
2、模擬某個數據文件在問題
shutdown immediate數據庫,然后拷貝moe01.dbf這個數據文件,然后打開數據庫,做日志切換,然后shutdown immediate,再把之前的拷貝替換現在的moe01.dbf數據文件
SYS@xbtst SQL>shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. [oracle@tstdb-25-220 xbtst]$ cp moe01.dbf moe01.dbf.bak [oracle@tstdb-25-220 xbtst]$ ll 總用量 3872076 -rw-r-----. 1 oracle oinstall 9748480 11月 10 09:48 control01.ctl -rw-r-----. 1 oracle oinstall 9748480 11月 10 09:48 control02.ctl -rw-r-----. 1 oracle oinstall 1073750016 11月 10 09:48 moe01.dbf -rw-r-----. 1 oracle oinstall 1073750016 11月 10 11:23 moe01.dbf.bak -rw-r-----. 1 oracle oinstall 52429312 11月 9 13:13 redo01.log -rw-r-----. 1 oracle oinstall 52429312 11月 9 22:00 redo02.log -rw-r-----. 1 oracle oinstall 52429312 11月 10 09:48 redo03.log -rw-r-----. 1 oracle oinstall 587210752 11月 10 09:48 sysaux01.dbf -rw-r-----. 1 oracle oinstall 807411712 11月 10 09:48 system01.dbf -rw-r-----. 1 oracle oinstall 30416896 11月 9 22:00 temp01.dbf -rw-r-----. 1 oracle oinstall 131080192 11月 10 09:48 undotbs01.dbf -rw-r-----. 1 oracle oinstall 111419392 11月 10 09:48 users01.dbf SYS@xbtst SQL>startup ORACLE instance started. Total System Global Area 2455228416 bytes Fixed Size 2255712 bytes Variable Size 620758176 bytes Database Buffers 1811939328 bytes Redo Buffers 20275200 bytes Database mounted. Database opened. SYS@xbtst SQL>alter system switch logfile; System altered. SYS@xbtst SQL>alter system switch logfile; System altered. SYS@xbtst SQL>alter system switch logfile; System altered. SYS@xbtst SQL>shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. [oracle@tstdb-25-220 xbtst]$ cp moe01.dbf moe01.dbf.bak.f [oracle@tstdb-25-220 xbtst]$ cp moe01.dbf.bak moe01.dbf 啟動數據庫報錯 SYS@xbtst SQL>startup ORACLE instance started. Total System Global Area 2455228416 bytes Fixed Size 2255712 bytes Variable Size 620758176 bytes Database Buffers 1811939328 bytes Redo Buffers 20275200 bytes Database mounted. ORA-01113: file 5 needs media recovery ORA-01110: data file 5: '/dbdata/oradata/xbtst/moe01.dbf' SYS@xbtst SQL>recover datafile 5; ORA-00279: change 1233063 generated at 11/10/2016 09:48:02 needed for thread 1 ORA-00289: suggestion : /apps/oracle/11.2.0/db_1/dbs/arch2_24_925478204.dbf ORA-00280: change 1233063 for thread 1 is in sequence #24 Specify log: {<RET>=suggested | filename | AUTO | CANCEL} auto ORA-00308: cannot open archived log '/apps/oracle/11.2.0/db_1/dbs/arch2_24_925478204.dbf' ORA-27037: unable to obtain file status Linux-x86_64 Error: 2: No such file or directory Additional information: 3 ORA-00308: cannot open archived log '/apps/oracle/11.2.0/db_1/dbs/arch2_24_925478204.dbf' ORA-27037: unable to obtain file status Linux-x86_64 Error: 2: No such file or directory Additional information: 3
3、場景模擬出來了,下面是修復過程
使用BBED,將文件頭的SCN等關鍵信息修改到與控制文件control file相匹配即可
SYS@xbtst SQL>select file#, CHECKPOINT_CHANGE# from v$datafile; FILE# CHECKPOINT_CHANGE# ---------- ------------------ 1 1233692 2 1233692 3 1233692 4 1233692 5 1233692 SYS@xbtst SQL>select CHECKPOINT_CHANGE# from v$database; CHECKPOINT_CHANGE# ------------------ 1233692 SYS@xbtst SQL>select file#, recover, fuzzy, CHECKPOINT_CHANGE# from v$datafile_header; FILE# REC FUZ CHECKPOINT_CHANGE# ---------- --- --- ------------------ 1 NO NO 1233692 2 NO NO 1233692 3 NO NO 1233692 4 NO NO 1233692 5 YES NO 1233063
控制文件中datafile5的scn是:1233692,而數據文件頭中的scn是:1233063
使用bbed將datafile5的數據文件頭對應的SCN修改為與其他文件相同,我們先看一下users01.dbf這個文件的文件頭
BBED> set filename '/dbdata/oradata/xbtst/users01.dbf' FILENAME /dbdata/oradata/xbtst/users01.dbf BBED> set block 1 BLOCK# 1 BBED> map File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Dba:0x00000000 ------------------------------------------------------------ Data File Header struct kcvfh, 860 bytes @0 ub4 tailchk @8188
因為我們要修改數據文件頭,因此我們需要關注四個偏移量offset點,分別為484、492、140和148
1、datafile 的file header 存儲在第一個block里
2、Oracle considers four attributes of this data structure when determining if a datafile is sync with the other data files of the database:(不同oracle版本offset可能不同)
(1)kscnbas (at offset 484) – SCN of last change to the datafile.
(2)kcvcptim (at offset 492) -Time of the last change to the datafile.
(3)kcvfhcpc (at offset 140) – Checkpoint count.
(4)kcvfhccc (at offset 148) – Unknown, but is always 1 less than thecheckpoint point count.
Oracle有4個屬性來判斷datafile 是否和其他的datafile 一致,如果都一致,可以正常操作,如果不一致,那么會報ORA-01113錯誤
下面我們看下這幾個offset
BBED> set offset 484 OFFSET 484 BBED> dump File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Offsets: 484 to 995 Dba:0x00000000 ------------------------------------------------------------------------ 1cd31200 00000000 bd384937 01000000 1b000000 30010000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 00000000 02000001 03000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> set offset 492 OFFSET 492 BBED> dump File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Offsets: 492 to 1003 Dba:0x00000000 ------------------------------------------------------------------------ bd384937 01000000 1b000000 30010000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 00000000 02000001 03000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> set offset 140 OFFSET 140 BBED> dump File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Offsets: 140 to 651 Dba:0x00000000 ------------------------------------------------------------------------ 78000000 14ff4737 77000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 04000000 05005553 45525300 00000000 00000000 00000000 00000000 00000000 00000000 04000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 7ac92131 01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 1cd31200 00000000 bd384937 01000000 1b000000 30010000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 <32 bytes per line> BBED> set offset 148 OFFSET 148 BBED> dump File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Offsets: 148 to 659 Dba:0x00000000 ------------------------------------------------------------------------ 77000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 04000000 05005553 45525300 00000000 00000000 00000000 00000000 00000000 00000000 04000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 7ac92131 01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 1cd31200 00000000 bd384937 01000000 1b000000 30010000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 <32 bytes per line>
其中,位于484和488偏移量的是數據文件對應的SCN編號。在Oracle內部,SCN是使用wrap*4*1024*1024*1024+base來進行標示的。通常我們看到的數據庫wrap都是0。位于492偏移量的是最后一次檢查點對應的時間信息。位于140和148偏移量的是檢查點次數。這些信息都是會由于時間推動和檢查點動作引起變化,我們嚴格情況下,需要保證文件頭塊的信息和控制文件信息一致。
另外一點,由于Linux是Little字節系統,要關注寫入時候的格式問題。最簡單的方式是dump一下偏移量,看看是怎么保存的。
BBED> dump File: /dbdata/oradata/xbtst/users01.dbf (0) Block: 1 Offsets: 484 to 995 Dba:0x00000000 ------------------------------------------------------------------------ 1cd31200 00000000 bd384937 01000000 1b000000 30010000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
然后我們修改moe01.dbf的文件頭(修改這幾個offset,我這里只修改了484、492就可以open庫了)
BBED> set filename '/dbdata/oradata/xbtst/moe01.dbf' FILENAME /dbdata/oradata/xbtst/moe01.dbf BBED> set block 1 BLOCK# 1 BBED> set mode edit MODE Edit BBED> set offset 484 OFFSET 484 BBED> dump File: /dbdata/oradata/xbtst/moe01.dbf (0) Block: 1 Offsets: 484 to 995 Dba:0x00000000 ------------------------------------------------------------------------ a7d01200 00000000 52204937 01000000 18000000 4d8d0000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 00000000 02004001 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> m /x 1cd31200 484 Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y File: /dbdata/oradata/xbtst/moe01.dbf (0) Block: 1 Offsets: 484 to 995 Dba:0x00000000 ------------------------------------------------------------------------ 1cd31200 00000000 52204937 01000000 18000000 4d8d0000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 00000000 02004001 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> m /x bd384937 492 BBED-00209: invalid number (bd384937) BBED> m /x bd38 492 File: /dbdata/oradata/xbtst/moe01.dbf (0) Block: 1 Offsets: 492 to 1003 Dba:0x00000000 ------------------------------------------------------------------------ bd384937 01000000 18000000 4d8d0000 100051f2 02000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 0d000d00 0d000100 00000000 00000000 00000000 02004001 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> m /x 4937 494 File: /dbdata/oradata/xbtst/moe01.dbf (0) Block: 1 Offsets: 494 to 1005 Dba:0x00000000 ------------------------------------------------------------------------ 49370100 00001800 00004d8d 00001000 51f20200 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000d00 0d000d00 01000000 00000000 00000000 00000200 40010000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 <32 bytes per line> BBED> sum apply Check value for File 0, Block 1: current = 0x1683, required = 0x1683 BBED> verify DBVERIFY - Verification starting FILE = /dbdata/oradata/xbtst/moe01.dbf BLOCK = 1 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 : 0 Total Blocks Influx : 0 Message 531 not found; product=RDBMS; facility=BBED
這時我們再次查看各個數據文件頭的scn,發現scn一致了
SYS@xbtst SQL>select file#, recover, fuzzy, CHECKPOINT_CHANGE# from v$datafile_header; FILE# REC FUZ CHECKPOINT_CHANGE# ---------- --- --- ------------------ 1 NO NO 1233692 2 NO NO 1233692 3 NO NO 1233692 4 NO NO 1233692 5 YES NO 1233692
試著open庫
SYS@xbtst SQL>alter database open 2 ; alter database open * ERROR at line 1: ORA-01113: file 5 needs media recovery ORA-01110: data file 5: '/dbdata/oradata/xbtst/moe01.dbf' SYS@xbtst SQL>recover datafile 5; Media recovery complete. SYS@xbtst SQL>alter database open; Database altered.
看一下alert文件
ALTER DATABASE RECOVER datafile 5 Media Recovery Start Serial Media Recovery started Media Recovery Complete (xbtst) Completed: ALTER DATABASE RECOVER datafile 5 Thu Nov 10 13:47:24 2016 alter database open Thu Nov 10 13:47:25 2016 Thread 1 opened at log sequence 27 Current log# 3 seq# 27 mem# 0: /dbdata/oradata/xbtst/redo03.log Successful open of redo thread 1 MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set Thu Nov 10 13:47:25 2016 SMON: enabling cache recovery [20910] Successfully onlined Undo Tablespace 2. Undo initialization finished serial:0 start:3710149144 end:3710149224 diff:80 (0 seconds) Verifying file header compatibility for 11g tablespace encryption.. Verifying 11g file header compatibility for tablespace encryption completed SMON: enabling tx recovery Database Characterset is AL32UTF8 No Resource Manager plan active replication_dependency_tracking turned off (no async multimaster replication found) Starting background process QMNC Thu Nov 10 13:47:25 2016 QMNC started with pid=20, OS id=21409 Completed: alter database open
在本次恢復過程中,recover是可行的,原因是該庫并沒做過resetlog,如果datafile是在 resetlog之前就已經offline的數據文件,那recover是不可行的。
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