RMAN深入解析之--BlockRecover恢复坏块



RMAN深入解析之--BlockRecover恢复坏块案例环境：操作系统：RedHatEL5Oracle：Oracle11gR2案例描述：通过块介质恢复（BlockMediaRecover:BMR)执行块级别的恢复操

RMAN深入解析之--BlockRecover恢复坏块

案例环境：

操作系统：RedHat EL5

Oracle： Oracle 11gR2

案例描述：

通过块介质恢复（Block Media Recover:BMR)执行块级别的恢复操作来修复Oracle数据库上的逻辑或物理上损坏的数据块。

1、模拟数据块被破坏

10:26:48 SYS@ prod>conn scott/tiger Connected. 10:26:51 SCOTT@ prod>select * from tab; TNAME TABTYPE CLUSTERID ------------------------------ ------- ---------- BONUS TABLE DEPT TABLE EMP TABLE EMP1 TABLE SALGRADE TABLE Elapsed: 00:00:00.10 10:26:55 SCOTT@ prod> 10:27:37 SYS@ prod>desc dba_segments Name Null? Type ----------------------------------------------------------------- -------- ------------- OWNER VARCHAR2(30) SEGMENT_NAME VARCHAR2(81) PARTITION_NAME VARCHAR2(30) SEGMENT_TYPE VARCHAR2(18) SEGMENT_SUBTYPE VARCHAR2(10) TABLESPACE_NAME VARCHAR2(30) HEADER_FILE NUMBER HEADER_BLOCK NUMBER BYTES NUMBER BLOCKS NUMBER EXTENTS NUMBER INITIAL_EXTENT NUMBER NEXT_EXTENT NUMBER MIN_EXTENTS NUMBER MAX_EXTENTS NUMBER MAX_SIZE NUMBER RETENTION VARCHAR2(7) MINRETENTION NUMBER PCT_INCREASE NUMBER FREELISTS NUMBER FREELIST_GROUPS NUMBER RELATIVE_FNO NUMBER BUFFER_POOL VARCHAR2(7) FLASH_CACHE VARCHAR2(7) CELL_FLASH_CACHE VARCHAR2(7) 10:27:41 SYS@ prod>col segment_name for a20 10:27:59 SYS@ prod>select owner,segment_name,SEGMENT_TYPE,HEADER_BLOCK from dba_segments 10:29:06 2 where owner='SCOTT' and segment_name='EMP1'; OWNER SEGMENT_NAME SEGMENT_TYPE HEADER_BLOCK ------------------------------ -------------------- ------------------ ------------ SCOTT EMP1 TABLE 170

通过以上查询，可以知道EMP1 table的segment header block为170；利用Uedit32，打开数据文件（users01.dbf)进行编辑破坏！

以下是计算block 170和block 171在Uedit32编辑中的offset：

10:29:24 SYS@ prod>select to_char(170*8*1024, 'xxxxxxxxxxxxxxxxxxxxx') from dual;

TO_CHAR(170*8*1024,'XX

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

154000

10:30:27 SYS@ prod>select to_char(171*8*1024, 'xxxxxxxxxxxxxxxxxxxxx') from dual;

TO_CHAR(171*8*1024,'XX

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

156000

以下是Uedit32编辑users01.dbf图片：

通过转储数据块验证：

10:30:37 SYS@ prod>alter system dump datafile 4 block 170;

System altered.

[oracle@rh6 ~]$ ls -lt /u01/app/oracle/diag/rdbms/prod/prod/trace/|more