dataguard file header corruption的模拟与修复

create tablespace test datafile  '/u01/app/oracle/oradata/prod/test.dbf' size 10M autoextend off;
create table test.test_corrupt tablespace test as select * from dba_objects where rownum<10000;

dd if=/dev/zero of=/u01/app/oracle/oradata/prod/test.dbf count=10 seek=131 bs=8192 conv=notrunc

此时自动的数据块修复
看到告警日志为：
Tue Mar 17 12:03:06 2015
Hex dump of (file 6, block 136) in trace file /u01/app/oracle/diag/rdbms/prod/prod/trace/prod_ora_2826.trc
Corrupt block relative dba: 0x01800088 (file 6, block 136)
Completely zero block found during multiblock buffer read
Reading datafile '/u01/app/oracle/oradata/prod/test.dbf' for corruption at rdba: 0x01800088 (file 6, block 136)
Reread (file 6, block 136) found same corrupt data (no logical check)
Starting background process ABMR
Tue Mar 17 12:03:06 2015
Corrupt Block Found
         TSN = 7, TSNAME = TEST
         RFN = 6, BLK = 136, RDBA = 25165960
         OBJN = 88622, OBJD = 88622, OBJECT = TEST_CORRUPT, SUBOBJECT = 
         SEGMENT OWNER = TEST, SEGMENT TYPE = Table Segment
Tue Mar 17 12:03:06 2015
ABMR started with pid=36, OS id=3706 
Automatic block media recovery service is active.
Automatic block media recovery requested for (file# 6, block# 136)
Tue Mar 17 12:03:08 2015
Automatic block media recovery successful for (file# 6, block# 136)
Automatic block media recovery successful for (file# 6, block# 136)


加大破坏力度：（此时会破坏文件头部）
dd if=/dev/zero of=/u01/app/oracle/oradata/prod/test.dbf count=100 seek=0 bs=8192 conv=notrunc

dbv校验下：
dbv file=/u01/app/oracle/oradata/prod/test.dbf blocksize=8192
DBV-00107: Unknown header format (0) (0)文件头损坏了。

文件头损坏：
[oracle@cell01 prod]$ dbfsize /u01/app/oracle/oradata/prod/testbk.dbf
/u01/app/oracle/oradata/prod/testbk.dbf: Header block magic number is bad

此时主库无法看到表：
SQL> select count(*) from test.test_corrupt;
select count(*) from test.test_corrupt
                         *
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 6, block # 131)
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'

主库告警日志发现，文件头损坏是不能恢复的
Tue Mar 17 12:07:59 2015
Dumping diagnostic data in directory=[cdmp_20150317120759], requested by (instance=1, osid=2826), summary=[incident=12153].
Automatic block media recovery requested for (file# 6, block# 131)
Automatic block media recovery failed for (file# 6, block# 131)
        [request flood controlled]
Errors in file /u01/app/oracle/diag/rdbms/prod/prod/trace/prod_ora_2826.trc  (incident=12154):
ORA-01578: ORACLE data block corrupted (file # 6, block # 131)
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'
Incident details in: /u01/app/oracle/diag/rdbms/prod/prod/incident/incdir_12154/prod_ora_2826_i12154.trc
Hex dump of (file 6, block 1) in trace file /u01/app/oracle/diag/rdbms/prod/prod/incident/incdir_12154/prod_ora_2826_i12154.trc
Corrupt block relative dba: 0x00000001 (file 6, block 1)
Completely zero block found during validating datafile for block range
Reread of blocknum=1, file=/u01/app/oracle/oradata/prod/test.dbf. found same corrupt data
Reread of blocknum=1, file=/u01/app/oracle/oradata/prod/test.dbf. found same corrupt data
Reread of blocknum=1, file=/u01/app/oracle/oradata/prod/test.dbf. found same corrupt data
Reread of blocknum=1, file=/u01/app/oracle/oradata/prod/test.dbf. found same corrupt data
Reread of blocknum=1, file=/u01/app/oracle/oradata/prod/test.dbf. found same corrupt data
Errors in file /u01/app/oracle/diag/rdbms/prod/prod/incident/incdir_12154/prod_ora_2826_i12154.trc:
ORA-19563: datafile header validation failed for file /u01/app/oracle/oradata/prod/test.dbf
ORA-01251: Unknown File Header Version read for file number 6
ORA-01578: ORACLE data block corrupted (file # 6, block # 131)
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'
Tue Mar 17 12:08:00 2015
Sweep [inc][12153]: completed
Sweep [inc2][12153]: completed
Dumping diagnostic data in directory=[cdmp_20150317120801], requested by (instance=1, osid=2826), summary=[incident=12154].

尝试手工修复吧，把好的文件从备库拿过来。（这种方法不可行）
备库执行：
SQL> select count(*) from test.test_corrupt;
  COUNT(*)
----------
      9999
recover managed standby database cancel;
copy file to primary db;

此时主库报错：
Tue Mar 17 12:12:39 2015
Read of datafile '/u01/app/oracle/oradata/prod/test.dbf' (fno 6) header failed with ORA-01208
Rereading datafile 6 header failed with ORA-01208
Errors in file /u01/app/oracle/diag/rdbms/prod/prod/incident/incdir_12155/prod_m002_3959_i12155_a.trc:
ORA-19583: conversation terminated due to error
ORA-01122: database file 6 failed verification check
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'
ORA-01208: data file is an old version - not accessing current version ---不是当前的版本，
Tue Mar 17 12:12:52 2015
Corrupt Block Found
         TSN = 7, TSNAME = TEST
         RFN = 6, BLK = 133, RDBA = 25165957
         OBJN = 88622, OBJD = 88622, OBJECT = TEST_CORRUPT, SUBOBJECT = 
         SEGMENT OWNER = TEST, SEGMENT TYPE = Table Segment

怎么办？
SQL> select count(*) from test.test_corrupt;
select count(*) from test.test_corrupt
                          *
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 6, block # 131)
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'
SQL> recover datafile 6;
ORA-00283: recovery session canceled due to errors
ORA-01124: cannot recover data file 6 - file is in use or recovery
ORA-01110: data file 6: '/u01/app/oracle/oradata/prod/test.dbf'

这种方法不可用，参考文档#
best Practices for Corruption Detection, Prevention, and Automatic Repair - in a Data Guard Configuration (文档 ID 1302539.1)
那么只有手工方式来修复file header了。
还是百度快，参考文档
http://blog.youkuaiyun.com/daimin1983/article/details/3225892
修正方法如下：
SQL> alter database create datafile '/u01/app/oracle/oradata/prod/test.dbf';
Database altered.

SQL> recover datafile 6;
ORA-00279: change 1081814 generated at 03/17/2015 11:44:17 needed for thread 1
ORA-00289: suggestion : /u01/app/oracle/oradata/prod_log/1_32_874356072.dbf
ORA-00280: change 1081814 for thread 1 is in sequence #32
Specify log: {=suggested | filename | AUTO | CANCEL}
auto
Log applied.
Media recovery complete.
SQL> alter database datafile 6 online;
Database altered.
SQL> select count(*) from test.test_corrupt;
  COUNT(*)
----------
      9999

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