最近需要迁移的3套rac数据中，检查发现都出现了坏块，而且部分坏块是未格式化的坏块，例如：
可以看到该坏块数据是写紊乱了，将file 147 block 805315的数据写入到file 34 block 3819968 中了。
通过如下sql查询可以发现属于未格式化的坏块，不属于任何对象：
虽然未格式化的坏块可能不会存在什么危险，在后面有业务数据插入时会进行将其格式化掉，但是由于坏块的存在，
导致rman备份无法成功，进而也就影响到我们这次的迁移测试了。
我这里利用vmware环境来模拟该问题，并给出解决方案，供大家参考！
----方法1 利用alter table xxx allocate extent
从上面信息可以看出，目前datafile 5中所分配的最大block号为2057+128-1=2184，换句话说以后的block都是空块。
我这里利用bbed来制造一个未格式化的坏块，也就是尚未利用的坏块(可能是已经分配但没有数据).
这里利用bbed随便修改一下，制造一个坏块如下：
下面我们来想办法格式化这个未格式化的坏块：
可以看到2200这个坏块已经包含在extent里面了，此时，我们来dbv检查一下。
----方法2 利用dd+bbed修复
下面我们使用dd来复制一个正常的未格式化block，将该坏块替换掉。
很显然，我们copy一个block过来替换以后，还不行，还得进行修改，此时你dbv检查可以看到仍然是坏块，如下：
下面我们利用bbed再进行适当修改即可，如下：
我们可以看到成功修复了该坏块。
*** SESSION ID:(1439.509) 2012-11-06 11:15:42.559
Start dump data blocks tsn: 7 file#: 34 minblk 3819968 maxblk 3819968
buffer tsn: 7 rdba: 0x24cc49c0 (147/805312)
scn: 0x001a.0e76f311 seq: 0x01 flg: 0x04 tail: 0xf3110601
frmt: 0x02 chkval: 0xf5c7 type: 0x06=trans data
Hex dump of corrupt header 4 = CORRUPT
Dump of memory from 0x000000011044D000 to 0x000000011044D014
11044D000 06A20000 24CC49C0 0E76F311 001A0104 [....$.I..v......]
11044D010 F5C70000 [....]
Hex dump of corrupt block
Dump of memory from 0x000000011044D014 to 0x000000011044EFFC
11044D010 01000000 0000D71A 0E76F311 [.........v..]
11044D020 001A2484 00023200 24CC4492 0014000D [..$...2.$.D.....]
11044D030 013EBCB7 015D1FF9 9BB43300 8000001A [.>...]....3.....]
......省略部分内容
11044EFD0 3D02C102 2C000306 C519232C 591706C5 [=...,.....#,Y...]
11044EFE0 18285F04 3102C102 2C000306 C519232C [.(_.1...,.....#,]
11044EFF0 591606C5 18285F04 3002C102 [Y....(_.0...]
End dump data blocks tsn: 7 file#: 34 minblk 3819968 maxblk 3819968
可以看到该坏块数据是写紊乱了，将file 147 block 805315的数据写入到file 34 block 3819968 中了。
通过如下sql查询可以发现属于未格式化的坏块，不属于任何对象：
select segment_name, segment_type, owner
from dba_extents
where file_id = < Absolute file number >
and < corrupted block
number > between block_id and block_id + blocks - 1;
select *
from dba_free_space
where file_id = < Absolute file number >
and < corrupted block
number > between block_id and block_id + blocks - 1;
虽然未格式化的坏块可能不会存在什么危险，在后面有业务数据插入时会进行将其格式化掉，但是由于坏块的存在，
导致rman备份无法成功，进而也就影响到我们这次的迁移测试了。
我这里利用vmware环境来模拟该问题，并给出解决方案，供大家参考！
----方法1 利用alter table xxx allocate extent
SQL> l
1* select file#,name,bytes/1024/1024 from v$datafile order by 1
SQL> /
FILE# NAME BYTES/1024/1024
---------- ------------------------------------------------------------ ---------------
1 /home/ora10g/oradata/roger/system01.dbf 770
2 /home/ora10g/oradata/roger/undotbs01.dbf 640
3 /home/ora10g/oradata/roger/sysaux01.dbf 320
4 /home/ora10g/oradata/roger/users01.dbf 298.75
5 /home/ora10g/oradata/roger/roger01.dbf 100
6 /home/ora10g/oradata/roger/undotb2_01.dbf 1
7 /home/ora10g/oradata/roger/test1.dbf 10
8 /home/ora10g/oradata/roger/sqlt_01.dbf 80
9 /home/ora10g/oradata/roger/undotbs03.dbf 500
9 rows selected.
SQL> select file_id,BLOCK_ID,BLOCKS from dba_free_space where file_id=5;
FILE_ID BLOCK_ID BLOCKS
---------- ---------- ----------
5 1009 24
5 2185 10616
SQL> select * from (select OWNER,SEGMENT_NAME,FILE_ID,EXTENT_ID,BLOCK_ID,BLOCKS from dba_extents where
2 file_id=5 order by 4 desc) where rownum < 5;
OWNER SEGMENT_NAME FILE_ID EXTENT_ID BLOCK_ID BLOCKS
----------- ----------------- ---------- ---------- ---------- ----------
GGS GGS_DDL_HIST 5 23 2057 128
GGS GGS_DDL_HIST 5 22 1929 128
GGS GGS_DDL_HIST 5 21 1801 128
GGS GGS_DDL_HIST 5 20 1673 128
SQL>
从上面信息可以看出，目前datafile 5中所分配的最大block号为2057+128-1=2184，换句话说以后的block都是空块。
我这里利用bbed来制造一个未格式化的坏块，也就是尚未利用的坏块(可能是已经分配但没有数据).
这里利用bbed随便修改一下，制造一个坏块如下：
[ora10g@killdb ~]$ dbv file=/home/ora10g/oradata/roger/roger01.dbf blocksize=8192 start=2000 end=2500
DBVERIFY: Release 10.2.0.5.0 - Production on Wed Nov 7 04:18:43 2012
Copyright (c) 1982, 2007, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /home/ora10g/oradata/roger/roger01.dbf
Page 2200 is marked corrupt
Corrupt block relative dba: 0x01400898 (file 5, block 2200)
Bad header found during dbv:
Data in bad block:
type: 58 format: 2 rdba: 0x01400bb8
last change scn: 0x0000.004d307d seq: 0x0 flg: 0x00
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x307d3a01
check value in block header: 0x968f
block checksum disabled
DBVERIFY - Verification complete
Total Pages Examined : 501
Total Pages Processed (Data) : 121
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 379
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 0
Total Pages Marked Corrupt : 1
Total Pages Influx : 0
Highest block SCN : 5374889 (0.5374889)
下面我们来想办法格式化这个未格式化的坏块：
SQL> conn roger/roger
Connected.
SQL> create table test_block as select * from dba_objects where 1=2;
Table created.
SQL> select sum(bytes/1024/1024) from dba_free_space where file_id=5;
SUM(BYTES/1024/1024)
--------------------
83.125
SQL> select blocks from v$datafile where file#=5;
BLOCKS
----------
12800
SQL> select (12800-2200)*8192/1024/1024 from dual;
(12800-2200)*8192/1024/1024
---------------------------
82.8125
SQL> alter table test_block move tablespace roger;
Table altered.
SQL> alter table test_block allocate extent(datafile '/home/ora10g/oradata/roger/roger01.dbf' size 10m);
Table altered.
SQL> alter table test_block nologging;
Table altered.
SQL> insert into test_block select * from dba_objects;
51079 rows created.
SQL> /
51079 rows created.
SQL> /
51079 rows created.
SQL> /
51079 rows created.
SQL> /
51079 rows created.
SQL> commit;
Commit complete.
SQL>
SQL> alter system checkpoint;
System altered.
SQL> alter system switch logfile;
System altered.
SQL> /
System altered.
SQL>
SQL> l
1 select owner,SEGMENT_NAME,EXTENT_ID,BLOCK_ID,BLOCKS
2* from dba_extents where SEGMENT_NAME='TEST_BLOCK' order by 3
SQL> /
OWNER SEGMENT_NAME EXTENT_ID BLOCK_ID BLOCKS
-------------- --------------- ---------- ---------- ----------
ROGER TEST_BLOCK 0 1009 8
ROGER TEST_BLOCK 1 2185 128
ROGER TEST_BLOCK 2 2313 128
ROGER TEST_BLOCK 3 2441 128
ROGER TEST_BLOCK 4 2569 128
ROGER TEST_BLOCK 5 2697 128
ROGER TEST_BLOCK 6 2825 128
ROGER TEST_BLOCK 7 2953 128
ROGER TEST_BLOCK 8 3081 128
ROGER TEST_BLOCK 9 3209 128
ROGER TEST_BLOCK 10 3337 128
ROGER TEST_BLOCK 11 3465 128
ROGER TEST_BLOCK 12 3593 128
ROGER TEST_BLOCK 13 3721 128
ROGER TEST_BLOCK 14 3849 128
ROGER TEST_BLOCK 15 3977 128
ROGER TEST_BLOCK 16 4105 128
ROGER TEST_BLOCK 17 4233 128
ROGER TEST_BLOCK 18 4361 128
ROGER TEST_BLOCK 19 4489 128
ROGER TEST_BLOCK 20 4617 128
ROGER TEST_BLOCK 21 4745 128
ROGER TEST_BLOCK 22 4873 128
ROGER TEST_BLOCK 23 5001 128
ROGER TEST_BLOCK 24 5129 128
ROGER TEST_BLOCK 25 5257 128
ROGER TEST_BLOCK 26 5385 128
ROGER TEST_BLOCK 27 5513 128
ROGER TEST_BLOCK 28 5641 128
29 rows selected.
可以看到2200这个坏块已经包含在extent里面了，此时，我们来dbv检查一下。
SQL> !
[ora10g@killdb ~]$ dbv file=/home/ora10g/oradata/roger/roger01.dbf blocksize=8192 start=2000 end=2500
DBVERIFY: Release 10.2.0.5.0 - Production on Wed Nov 7 04:30:00 2012
Copyright (c) 1982, 2007, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /home/ora10g/oradata/roger/roger01.dbf
DBVERIFY - Verification complete
Total Pages Examined : 501
Total Pages Processed (Data) : 431
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 70
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 0
Total Pages Marked Corrupt : 0
Total Pages Influx : 0
Highest block SCN : 5519642 (0.5519642)
我们可以看到，该未格式化的坏块已经被修复了，最后我们再将创建的临时表删除即可。
[ora10g@killdb ~]$ exit
exit
SQL> drop table test_block purge;
Table dropped.
SQL>
----方法2 利用dd+bbed修复
先制造一个未格式化的坏块：
BBED> set file 5 block 2500
FILE# 5
BLOCK# 2500
BBED> modify /x 100 offset 14
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
File: /home/ora10g/oradata/roger/roger01.dbf (5)
Block: 2500 Offsets: 14 to 33 Dba:0x014009c4
------------------------------------------------------------------------
0100a0e4 00000100 000011e5 00001639 54000000
<32 bytes per line>
BBED> sum apply
Check value for File 5, Block 2500:
current = 0xe4a0, required = 0xe4a0
BBED> verify
DBVERIFY - Verification starting
FILE = /home/ora10g/oradata/roger/roger01.dbf
BLOCK = 2500
Block 2500 is corrupt
Corrupt block relative dba: 0x014009c4 (file 0, block 2500)
Fractured block found during verification
Data in bad block:
type: 6 format: 2 rdba: 0x014009c4
last change scn: 0x0000.00543916 seq: 0x1 flg: 0x00
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x39160604
check value in block header: 0xe4a0
block checksum disabled
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 : 1
Total Blocks Influx : 2
[ora10g@killdb ~]$ dbv file=/home/ora10g/oradata/roger/roger01.dbf start=2000 end=3000
DBVERIFY: Release 10.2.0.5.0 - Production on Wed Nov 7 04:49:28 2012
Copyright (c) 1982, 2007, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /home/ora10g/oradata/roger/roger01.dbf
Page 2500 is influx - most likely media corrupt
Corrupt block relative dba: 0x014009c4 (file 5, block 2500)
Fractured block found during dbv:
Data in bad block:
type: 6 format: 2 rdba: 0x014009c4
last change scn: 0x0000.00543916 seq: 0x1 flg: 0x00
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x39160604
check value in block header: 0xe4a0
block checksum disabled
DBVERIFY - Verification complete
Total Pages Examined : 1001
Total Pages Processed (Data) : 922
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 78
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 0
Total Pages Marked Corrupt : 1
Total Pages Influx : 1
Highest block SCN : 5519647 (0.5519647)
下面我们使用dd来复制一个正常的未格式化block，将该坏块替换掉。
[ora10g@killdb ~]$ dd if=/home/ora10g/oradata/roger/roger01.dbf of=/tmp/dd_block skip=2502 bs=8192 count=1
1+0 records in
1+0 records out
[ora10g@killdb ~]$
[ora10g@killdb ~]$ dd if=/tmp/dd_block of=/home/ora10g/oradata/roger/roger01.dbf seek=2500 bs=8192 count=1 conv=notrunc
1+0 records in
1+0 records out
[ora10g@killdb ~]$
很显然，我们copy一个block过来替换以后，还不行，还得进行修改，此时你dbv检查可以看到仍然是坏块，如下：
[ora10g@killdb ~]$ dbv file=/home/ora10g/oradata/roger/roger01.dbf start=2000 end=3000
DBVERIFY: Release 10.2.0.5.0 - Production on Wed Nov 7 04:51:34 2012
Copyright (c) 1982, 2007, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /home/ora10g/oradata/roger/roger01.dbf
Page 2500 is marked corrupt
Corrupt block relative dba: 0x014009c4 (file 5, block 2500)
Bad header found during dbv:
Data in bad block:
type: 6 format: 2 rdba: 0x014009c6
last change scn: 0x0000.00543916 seq: 0x4 flg: 0x04
spare1: 0x0 spare2: 0x0 spare3: 0x0
consistency value in tail: 0x39160604
check value in block header: 0xfe93
computed block checksum: 0x0
DBVERIFY - Verification complete
Total Pages Examined : 1001
Total Pages Processed (Data) : 922
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 78
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 0
Total Pages Marked Corrupt : 1
Total Pages Influx : 0
Highest block SCN : 5519647 (0.5519647)
下面我们利用bbed再进行适当修改即可，如下：
BBED> set file 5 block 2501
FILE# 5
BLOCK# 2501
BBED> d /v count 20
File: /home/ora10g/oradata/roger/roger01.dbf (5)
Block: 2501 Offsets: 0 to 19 Dba:0x014009c5
-------------------------------------------------------
06a20000 c5094001 16395400 00000404 l ..@..9T.....
d52b0000 l ..
<16 bytes per line>
BBED> set file 5 block 2500
FILE# 5
BLOCK# 2500
BBED> modify /x c4 offset 4
File: /home/ora10g/oradata/roger/roger01.dbf (5)
Block: 2500 Offsets: 4 to 33 Dba:0x014009c4
------------------------------------------------------------------------
c4094001 16395400 00000404 93fe0000 01000000 11e50000 16395400 0000
<32 bytes per line>
BBED> sum apply
Check value for File 5, Block 2500:
current = 0xfe91, required = 0xfe91
BBED> verify
DBVERIFY - Verification starting
FILE = /home/ora10g/oradata/roger/roger01.dbf
BLOCK = 2500
DBVERIFY - Verification complete
Total Blocks Examined : 1
Total Blocks Processed (Data) : 1
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
[ora10g@killdb ~]$ dbv file=/home/ora10g/oradata/roger/roger01.dbf start=2000 end=3000
DBVERIFY: Release 10.2.0.5.0 - Production on Wed Nov 7 05:13:29 2012
Copyright (c) 1982, 2007, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /home/ora10g/oradata/roger/roger01.dbf
DBVERIFY - Verification complete
Total Pages Examined : 1001
Total Pages Processed (Data) : 923
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 78
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 0
Total Pages Marked Corrupt : 0
Total Pages Influx : 0
Highest block SCN : 5519647 (0.5519647)
我们可以看到成功修复了该坏块。
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