【Oracle数据恢复】ORA-01122,ORA-01110,ORA-01200错误解析

偶尔我们会遇到ORA-01122,ORA-01110,ORA-01200错误,例如:

 

ORA-01122: database file 9 failed verification check
ORA-01110: data file 9: '/u02/oradata/orcl/users01.dbf '
ORA-01200: actual file size of 64000 is smaller than correct size of 65600


[oracle@mlab2 ~]$ oerr ora 1122
01122, 00000, "database file %s failed verification check"
// *Cause:  The information in this file is inconsistent with information
//         from the control file. See accompanying message for reason.
// *Action: Make certain that the db files and control files are the correct
//         files for this database.


[oracle@mlab2 ~]$ oerr ora 1110
01110, 00000, "data file %s: '%s'"
// *Cause:  Reporting file name for details of another error. The reported
//          name can be of the old file if a data file move operation is
//          in progress.
// *Action: See associated error message.


[oracle@mlab2 ~]$ oerr ora 1200
01200, 00000, "actual file size of %s is smaller than correct size of %s blocks"
// *Cause:  The size of the file as returned by the operating system is smaller
//         than the size of the file as indicated in the file header and the
//         control file. Somehow the file has been truncated. Maybe it is the
//         result of a half completed copy.
// *Action: Restore a good copy of the data file and do recovery as needed.

以上ORA-1200错误的描述是 当数据文件的实际大小 小于了数据文件头描述的块数*block_size, 这里所说的文件实际大小是通过OS层的系统调用获得的; 这种现象一般意味着数据文件可能被截断了。

 

 

注意,当备份和归档备份完备的情况下可以直接还原备份来修复该问题,本文特定针对那些无备份的情况下遇到该问题的解决。建议对于SYSTEM表空间下的数据文件不要尝试这样修复。

 

首先有必要的是对数据库做一个全库的冷备,分析ORA-01110 和 ORA-01122的报错 可以了解到对应存在问题的具体数据文件号,如下面显然是FILE#=9的文件出错了:

 

ORA-01122: database file 9 failed verification check
ORA-01110: data file 9: '/u02/oradata/orcl/users01.dbf '

 

 

在上面的例子中ORA-01200: actual file size of 64000 is smaller than correct size of 65600,即实际的文件大小为64000*db_block_size+1个Oracle BLock=64000 * 8192 + 8192 =524296192

具体是不是这么大,可以通过 ls -ltr 数据文件   来确定。

 

但是ORACLE从数据文件头中获取的数据文件理论大小是65600 –> 65000 * 8192 +8192=532488192 bytes。

 

由此比较2者会发现存在65600-64000=1600个块的差距,这1600个块的差距可以通过dd来实现添加到现有的数据文件中,当然这里加的是空块。

例如:

 

dd if=<locationf datafile having problem> of=<output/target datafile> count=< > bs=<db_block_size in bytes>

如dd if=/u02/oradata/orcl/users01.dbf of=/tmp/corr_temp.DBF count=64000 bs=8192

并追加1600个空块到新的数据文件里

dd if=/dev/zero of=<location of datafile> bs=<db_block_size in bytes> seek=<Actual block number reported + 1 > count=<Difference in number of block>

如dd if=/dev/zero of=/u02/oradata/careware/users01.dbf bs=8192 seek=64001 count=1600 conv=notrun


 

由于数据库打开时仅仅验证数据文件头和控制文件信息,所以上述操作能够骗过ORACLE的检测。 但扔建议在数据库打开后,将所有可用数据导出并重建数据库。

 

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