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/tigerconnected.10:26:51 scott@ prod>select * from tab;tname                          tabtype  clusterid------------------------------ ------- ----------bonus                          tabledept                           tableemp                            tableemp1                           tablesalgrade                       tableelapsed: 00:00:00.1010:26:55 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