[20150527]bbed解决数据文件大小问题.txt
--模拟一个数据文件大小不一致的问题.
1.建立测试环境:
SCOTT@test> @ &r/ver1
PORT_STRING VERSION BANNER
------------------------------ -------------- ----------------------------------------------------------------
x86_64/Linux 2.4.xx 10.2.0.4.0 Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
SCOTT@test> select file#,name,bytes from v$datafile ;
FILE# NAME BYTES
----- --------------------------------- ------------
1 /mnt/ramdisk/test/system01.dbf 534773760
2 /mnt/ramdisk/test/undotbs01.dbf 367001600
3 /mnt/ramdisk/test/sysaux01.dbf 387973120
4 /mnt/ramdisk/test/users01.dbf 104857600
5 /mnt/ramdisk/test/example01.dbf 104857600
6 /mnt/ramdisk/test/mssm01.dbf 16777216
6 rows selected.
$ ls -l /mnt/ramdisk/test/mssm01.dbf
-rw-r----- 1 oracle oinstall 16785408 2015-05-27 10:52:05 /mnt/ramdisk/test/mssm01.dbf
16785408-16777216=8192
--可以发现视图v$datafile显示的与os看的有8192字节差距,实际上前面1块OS块,记录一个OS信息.
--16777216=16M,不好观察数据文件的大小的定义在什么位置.
SCOTT@test> select (16777216-2*64*1024)/1024 from dual ;
(16777216-2*64*1024)/1024
-------------------------
16256
SCOTT@test> ALTER DATABASE DATAFILE '/mnt/ramdisk/test/mssm01.dbf' RESIZE 16256K;
Database altered.
16256/8=2032
2032 = 0x7f0
--通过bbed观察:
BBED> set dba 6,1
DBA 0x01800001 (25165825 6,1)
BBED> p kcvfhhdr
struct kcvfhhdr, 76 bytes @20
ub4 kccfhswv @20 0x00000000
ub4 kccfhcvn @24 0x0a200300
ub4 kccfhdbi @28 0x80f1c038
text kccfhdbn[0] @32 T
text kccfhdbn[1] @33 E
text kccfhdbn[2] @34 S
text kccfhdbn[3] @35 T
text kccfhdbn[4] @36
text kccfhdbn[5] @37
text kccfhdbn[6] @38
text kccfhdbn[7] @39
ub4 kccfhcsq @40 0x33c3d8a7
ub4 kccfhfsz @44 0x000007f0
--应该是kcvfhhdr.kccfhfsz字段.
2.安全第1,关闭数据库,做一个冷备份:
--步骤忽略.
3.修改偏移量44,45:
--FF,7F ,注意要反过来. 相当于修改为07FF=2047.
BBED> sum apply
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
Check value for File 6, Block 1:
current = 0x9632, required = 0x9632
4.启动数据库观察:
SYS@test> startup
ORACLE instance started.
Total System Global Area 473956352 bytes
Fixed Size 2084776 bytes
Variable Size 260046936 bytes
Database Buffers 201326592 bytes
Redo Buffers 10498048 bytes
Database mounted.
ORA-01122: database file 6 failed verification check
ORA-01110: data file 6: '/mnt/ramdisk/test/mssm01.dbf'
ORA-01200: actual file size of 2032 is smaller than correct size of 2047 blocks
5.修改很简单,修改原来的44,45字节为正确的 2032 = 0x7f0.
BBED> set dba 6,1
DBA 0x01800001 (25165825 6,1)
BBED> p kcvfhhdr.kccfhfsz
ub4 kccfhfsz @44 0x000007ff
BBED> modify /x f007
BBED> p kcvfhhdr.kccfhfsz
ub4 kccfhfsz @44 0x000007f0
BBED> sum apply
Check value for File 6, Block 1:
current = 0x963d, required = 0x963d
SYS@test> startup
ORACLE instance started.
Total System Global Area 473956352 bytes
Fixed Size 2084776 bytes
Variable Size 260046936 bytes
Database Buffers 201326592 bytes
Redo Buffers 10498048 bytes
Database mounted.
Database opened.
--OK现在正常了,这种错误可能出现磁盘满了,而空间增加的情况,不过真实的模拟存在一些难度,至少我没有模拟出来.修改方法应该就像上面的介绍.
