在数据恢复实践(一)中,我们了解到在 Windows 的11.2.0.1的环境中恢复过程比较顺利,那么接下来的测试,是我遇到更加复杂的情况:系统表空间保护两个不连续的系统文件;恢复过程中出现 ORA 错误及数据字典不匹配的情况。我借助了一些非常规的手段规避这些问题,达到数据拯救的目的。
概述
这个数据拯救的测试中,环境更加复杂:旧数据库异常关闭;旧数据库仅剩下三个数据文件,其中两个属于系统表空间且文件号不连续,其它文件,诸如控制文件、在线日志文件、UNDO 表空间文件、临时表空间及其它数据文件都已丢失。因此在数据恢复过程中也遇到更多的问题。
同样,需要先获得数据库版本、数据库名称和原始的数据文件位置及大小等信息,设置 SID 和密码。
以下为参数文件内容:
_allow_resetlogs_corruption = true control_files = (/opt/oracle/oradata/ORA10R2/control/ora_control1, /opt/oracle/oradata/ORA10R2/control/ora_control2, /opt/oracle/oradata/ORA10R2/control/ora_control3) db_name = ORA10R2 db_domain = "" db_block_size = 8192 undo_management = manual undo_tablespace = '' UNDO_RETENTION = 900 nls_language = "AMERICAN" nls_territory = "AMERICA" user_dump_dest = /opt/oracle/admin/ORA10R2/udump background_dump_dest = /opt/oracle/admin/ORA10R2/bdump core_dump_dest = /opt/oracle/admin/ORA10R2/cdump sga_max_size = 200M sga_target = 200M
然后创建新库:
SQL> CREATE DATABASE ORA10R2 USER SYS IDENTIFIED BY oracle USER SYSTEM IDENTIFIED BY oracle LOGFILE GROUP 1 ('/opt/oracle/oradata/ORA10R2/onlinelog/redo01.log') SIZE 20M, GROUP 2 ('/opt/oracle/oradata/ORA10R2/onlinelog/redo02.log') SIZE 20M, GROUP 3 ('/opt/oracle/oradata/ORA10R2/onlinelog/redo03.log') SIZE 20M MAXLOGFILES 5 MAXLOGMEMBERS 5 MAXLOGHISTORY 1 MAXDATAFILES 100 MAXINSTANCES 1 CHARACTER SET US7ASCII NATIONAL CHARACTER SET AL16UTF16 DATAFILE '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_200m' SIZE 180M REUSE --, '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_02' SIZE 200M REUSE EXTENT MANAGEMENT LOCAL SYSAUX DATAFILE '/opt/oracle/oradata/ORA10R2/datafile/sysaux01' SIZE 100M DEFAULT TEMPORARY TABLESPACE tempts1 TEMPFILE '/opt/oracle/oradata/ORA10R2/datafile/temp01' SIZE 20M --UNDO TABLESPACE undotbs1 --DATAFILE '/opt/oracle/oradata/ORA10R2/datafile/undotbs01' --SIZE 500M AUTOEXTEND ON NEXT 5120K MAXSIZE UNLIMITED ; 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Database created.
因为我们旧的系统表空间中有两个不连续的数据文件,因此我们需要想办法创建出相应文件号的数据文件。
1、首先,我们用 BBED 可以看到第二个
数据文件的文件号:
BBED> p kcvfh ... ub2 kccfhfno @52 0x0008 ...
2、为了让新的系统文件号为8,我们需
要创建几个临时的数据文件提高文件
号,然后再添加新的系统文件:
SQL> create tablespace test datafile '/opt/oracle/oradata/ORA10R2/datafile/test3' size 10M, '/opt/oracle/oradata/ORA10R2/datafile/test4' size 10M, '/opt/oracle/oradata/ORA10R2/datafile/test5' size 10M, '/opt/oracle/oradata/ORA10R2/datafile/test6' size 10M, '/opt/oracle/oradata/ORA10R2/datafile/test7' size 10M; alter tablespace system add datafile '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_02' size 200M; DROP TABLESPACE test INCLUDING CONTENTS AND DATAFILES; Tablespace created. SQL> Tablespace altered. SQL> Tablespace dropped.
如果这里我们按照之前11g 的过程继续操作,将会遇到大量错误,诸如 ORA-00600 [4000], ORA-01555, ORA-01111, ORA-01173, ORA-00600 [4049] 等等。经过深入分析,发现导致这些错误的最终原因是:一致性读。
因为新库创建后,其 Checkpoint SCN 非常小,因此在 Bootstrap 过程中读取系统数据字典数据块时,与数据块上的 ITL 中 scn 比较,发现需要进行一致性回滚,因而会读取回滚段数据,但这些回滚段通常都是不存在,因此会导致以上诸多错误的出现。
当然,这也产生了一个疑问:为什么在 11g 的恢复过程没有发生这些问题?通过对比发现,在11g 的恢复过程中,NID 操作重新设置了系统文件中的 Checkpoint SCN,使其恢复为其原来的 SCN。因为我们已经将其文件头替换为新文件的文件头,因此我猜测 NID 过程中读取了数据字典中 SCN 信息,并重写的文件头。从 nid 过程抛出的 ORA-00600 错误也可以看到,它调用了系统的内部包完成 ID 修改过程。
但在10g 的 NID 过程,并没有修改 SCN,因此需要我们手动提高 SCN。
这里,我使用了隐含参数_minimum_giga_scn。设置该参数,我们需要观察 alert log,因为数值太小不会成功,日志中出现以下记录。
Current SCN is not changed: _minimum_giga_scn (scn 274877906944) is too small
我们这里设置_minimum_giga_scn = 1024,重启数据库,alert 日志提示设置成功。
Advancing SCN to 1099511627776 according to _minimum_giga_scn
3、接下来重命名新系统文件,拷贝旧数
据文件到当前数据文件目录:
[oracle@server1 ORA10R2]$ mv datafile/ORA10R2_system_200m datafile/ORA10R2_system_200m_new [oracle@server1 ORA10R2]$ mv datafile/ORA10R2_system_02 datafile/ORA10R2_system_02_new [oracle@server1 ORA10R2]$ cp ../ORA10R2_COPY/datafile/ORA10R2_system_200m ./datafile/ [oracle@server1 ORA10R2]$ cp ../ORA10R2_COPY/datafile/ORA10R2_system_02 ./datafile/ [oracle@server1 ORA10R2]$ cp ../ORA10R2_COPY/datafile/ORA10R2_example_50m ./datafile/
4、然后执行 nid 修改数据库 ID(不过我认
为这一步在这里已经不重要了):
[oracle@server1 ORA10R2]$ nid target=sys/oracle DBNEWID: Release 10.2.0.1.0 - Production on Tue Mar 19 00:44:33 2013 ... ... Database ID for database ORA10R2 changed to 4153675250. All previous backups and archived redo logs for this database are unusable. Database has been shutdown, open database with RESETLOGS option. Succesfully changed database ID. DBNEWID - Completed succesfully.
5、重建控制文件,并恢复、OPEN
RESETLOGS:
SQL> CREATE CONTROLFILE REUSE DATABASE ORA10R2 RESETLOGS NOARCHIVELOG MAXLOGFILES 5 MAXLOGMEMBERS 5 MAXDATAFILES 100 MAXINSTANCES 1 MAXLOGHISTORY 292 LOGFILE GROUP 1 '/opt/oracle/oradata/ORA10R2/onlinelog/redo01.log' SIZE 20M, GROUP 2 '/opt/oracle/oradata/ORA10R2/onlinelog/redo02.log' SIZE 20M, GROUP 3 '/opt/oracle/oradata/ORA10R2/onlinelog/redo03.log' SIZE 20M DATAFILE '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_200m' SIZE 180M , '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_02' SIZE 200M --, '/opt/oracle/oradata/ORA10R2/datafile/sysaux01' size 100M --, '/opt/oracle/oradata/ORA10R2/datafile/undotbs01' CHARACTER SET US7ASCII ; 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Control file created. SQL> recover database using backup controlfile until cancel; ORA-00279: change 1099511627897 generated at 03/19/2013 00:43:31 needed for thread 1 ORA-00289: suggestion : /opt/oracle/product/10.2.0/db/dbs/arch1_2_810434521.dbf ORA-00280: change 1099511627897 for thread 1 is in sequence #2 Specify log: {<RET>=suggested | filename | AUTO | CANCEL} cancel Media recovery cancelled. SQL> alter database open resetlogs; alter database open resetlogs * ERROR at line 1: ORA-01092: ORACLE instance terminated. Disconnection forced
6、数据库打开失败,从 alert 日志看到错
误内容为:
ORA-01177: data file does not match dictionary - probably old incarnation ORA-01110: data file 1: '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_200m'
7、再次执行恢复和打开过程,并启动
10046 事件跟踪,从跟踪内容中看
到引起该错误的语句及等待事件:
PARSING IN CURSOR #2 len=122 dep=1 uid=0 oct=3 lid=0 tim=1331710783410619 hv=1330125001 ad='2c3341c8' select blocks,NVL(ts#,-1),status$,NVL(relfile#,0),maxextend,inc, crscnwrp,crscnbas,NVL(spare1,0) from file$ where file#=:1 END OF STMT PARSE #2:c=0,e=300,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,tim=1331710783410615 BINDS #2: kkscoacd Bind#0 oacdty=02 mxl=22(22) mxlc=00 mal=00 scl=00 pre=00 oacflg=08 fl2=0001 frm=00 csi=00 siz=24 off=0 kxsbbbfp=b71e3928 bln=22 avl=02 flg=05 value=1 EXEC #2:c=1000,e=574,p=0,cr=0,cu=0,mis=1,r=0,dep=1,og=4,tim=1331710783411304 WAIT #2: nam='db file sequential read' ela= 14 file#=1 block#=258 blocks=1 obj#=-1 tim=1331710783411361 WAIT #2: nam='db file sequential read' ela= 10 file#=1 block#=114 blocks=1 obj#=-1 tim=1331710783411419 ... ORA-01177: data file does not match dictionary - probably old incarnation ORA-01110: data file 1: '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_200m'
显然,启动进程读取了数据字典 file$ 的数据(第114块数据块),再与数据文件头中的信息对比,存在不匹配数据,则抛出1777 错误。
处理1777错误前,我们启动 mount 状态,并做文件恢复。
SQL> startup mount SQL> recover datafile 1 Media recovery complete. SQL> recover datafile 8 Media recovery complete.
用 bbed 打开114号数据块,即file$的数据块,查看第一条记录,即文件1的数据。
BBED> set file 1 block 114 FILE# 1 BLOCK# 114 BBED> p *kdbr[0] BBED> x /rnnnnnnnnnnnnnnnnnnnnnnnnnnn rowdata[678] @8153 ------------ flag@8153: 0x2c (KDRHFL, KDRHFF, KDRHFH) lock@8154: 0x00 cols@8155: 11 col 0[2] @8156: 1 -- FILE# col 1[2] @8159: 2 -- STATUS$ col 2[4] @8162: 23040 -- BLOCKS col 3[1] @8167: 0 -- TS# col 4[2] @8169: 1 -- RELFILE# col 5[1] @8172: 0 -- MAXEXTEND col 6[1] @8174: 0 -- INC col 7[1] @8176: 0 -- CRSCNWRP col 8[2] @8178: 8 -- CRSCNBAS col 9[0] @8181: *NULL* -- OWNERINSTANCE col 10[5] @8182: 4194306 -- SPARE1
再打开文件头,可以发现 create scn (CRSCNWRP, CRSCNBAS) 不匹配。
BBED> set file 1 block 1 BBED> map BBED> p kcvfh struct kcvfh, 676 bytes @0 struct kcvfhbfh, 20 bytes @0 ub1 type_kcbh @0 0x0b ub1 frmt_kcbh @1 0xa2 ub1 spare1_kcbh @2 0x00 ... struct kcvfhcrs, 8 bytes @100 ub4 kscnbas @100 0x00000006 -- CRSCNBAS ub2 kscnwrp @104 0x0000 -- CRSCNWRP ... struct kcvfhckp, 36 bytes @484 struct kcvcpscn, 8 bytes @484 ub4 kscnbas @484 0x00006fa4 -- CKPCNBAS ub2 kscnwrp @488 0x0100 -- CKPCNWRP ...
要规避这个问题,就需要使数据字典中的数据与文件头中的信息一致。这里我修改了数据字典当中的数据。
用 dump 函数看我们需要写入什么数据:
SQL> select dump(6,16) from dual; DUMP(8,16) ----------------- Typ=2 Len=2: c1,7
然后用 BBED 修改该记录:
BBED> set file 1 block 114 BBED> dump offset 8178 count 4 BBED> modify /x 02c107ff BBED> sum apply
接下来避免8号文件出现同样错误,同样修改其记录。
8号文件头数据:
struct kcvfhcrs, 8 bytes @100 ub4 kscnbas @100 0x00001c64 ub2 kscnwrp @104 0x0000
数据字典数据:
col 0[2] @7478: 8 col 1[2] @7481: 2 col 2[3] @7484: 25600 col 3[1] @7488: 0 col 4[2] @7490: 8 col 5[1] @7493: 0 col 6[1] @7495: 0 col 7[1] @7497: 0 col 8[4] @7499: 140113 col 9[0] @7504: *NULL* col 10[5] @7505: 33554434
Dump 结果:
SQL> select dump(7268,16) from dual; DUMP(7268,16) --------------------- Typ=2 Len=3: c2,49,45 SQL> select dump(140113,16) from dual; DUMP(140113,16) --------------------- Typ=2 Len=4: c3,f,2,e
再用 BBED 修改。
BBED> dump offset 7499 count 6 BBED> modify /x 04c24945 BBED> sum apply
修改完成后,开启数据库成功,并读取出旧数据库中数据字典内容:
SQL> alter database open; Database altered. SQL> select file_id, tablespace_name from dba_data_files where tablespace_name like '%EXAMPLE%'; FILE_ID TABLESPACE_NAME ---------- ------------------------------ 4 EXAMPLE SQL> select file#, name from v$datafile where file#=4; FILE# NAME ---------- -------------------------------------------------------------------------------- 4 /opt/oracle/product/10.2.0/db/dbs/MISSING00004
重命名数据文件:
SQL> ALTER DATABASE RENAME FILE '/opt/oracle/product/10.2.0/db/dbs/MISSING00004' TO '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m'; Database altered.
重新恢复数据库,使数据文件 ONLINE:
SQL> shutdown ... ... SQL> recover database until cancel; Media recovery complete. SQL> ALTER DATABASE DATAFILE '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m' ONLINE; Database altered. SQL> alter database open resetlogs; alter database open resetlogs * ERROR at line 1: ORA-01122: database file 4 failed verification check ORA-01110: data file 4: '/opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m' ORA-01206: file is not part of this database - wrong database id
在打开数据库时,抛错,指示加入的数据文件的数据库 ID 不匹配。
通过其他文件可以看到当前数据库的 DBID:
BBED> set file 1 block 1 FILE# 1 BLOCK# 1 BBED> p kcvfh ... ub4 kccfhdbi @28 0xf7940df2 ... BBED> dump offset 28 count 4 File: /opt/oracle/oradata/ORA10R2/datafile/ORA10R2_system_200m (1) Block: 1 Offsets: 28 to 31 Dba:0x00400001 ------------------------------------------------------------------------ f20d94f7
通过 BBED 修改 ID:
BBED> set file 4 block 1 FILE# 4 BLOCK# 1 BBED> p kcvfh ... ub4 kccfhdbi @28 0xb9888c45 ... BBED> dump offset 30 count 2 File: /opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m (4) Block: 1 Offsets: 30 to 31 Dba:0x01000001 ------------------------------------------------------------------------ 88b9 BBED> modify /x 94f7 File: /opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m (4) Block: 1 Offsets: 30 to 31 Dba:0x01000001 ------------------------------------------------------------------------ 94f7 BBED> dump offset 28 count 4 File: /opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m (4) Block: 1 Offsets: 28 to 31 Dba:0x01000001 ------------------------------------------------------------------------ f29d94f7 BBED> modify /x f20d File: /opt/oracle/oradata/ORA10R2/datafile/ORA10R2_example_50m (4) Block: 1 Offsets: 28 to 31 Dba:0x01000001 ------------------------------------------------------------------------ f20d94f7 BBED> sum apply Check value for File 4, Block 1: current = 0x4460, required = 0x4460
再次启动,成功!
SQL> alter database open resetlogs; Database altered.
创建临时表空间,修改用户:
SQL> CREATE TEMPORARY TABLESPACE temp2 TEMPFILE '/opt/oracle/oradata/ORA10R2/datafile/temp02' size 100M; Tablespace created. SQL> select 'ALTER USER '||username||' TEMPORARY TABLESPACE TEMP2;' from dba_users; 'ALTERUSER'||USERNAME||'TEMPORARYTABLESPACETEMP2;' --------------------------------------------------------------------- ALTER USER STMADMIN TEMPORARY TABLESPACE TEMP2; ... ... SQL> ALTER USER STMADMIN TEMPORARY TABLESPACE TEMP2; ... ... User altered.
用 EXP 导出数据:
[oracle@server1 ORA10R2]$ exp system/oracle tablespaces=EXAMPLE file=resecue.dat log=resecue.log ... ... . . exporting table USR_MV 11 rows exported . exporting referential integrity constraints . exporting triggers Export terminated successfully without warnings.
数据已经成功拯救出来。
不过,这两个测试都是在实验环境当中的,实际情况可能更为复杂。这个恢复方法只能视为一根救命稻草,真正能保证数据安全的还是完善的备份计划和容灾方案。