ORA-00600 [2662]错误解决

   客户报修，客户端软件无法连接服务器，数据库版本为10205,查看数据库日志信息发下如下错误信息：

Tue Jun 25 12:02:52 CST 2013
Errors in file /home/oracle/orabase/admin/ORACLE/bdump/oracle_q000_3529.trc:
ORA-00600: internal error code, arguments: [2662], [0], [91108808], [0], [91133612], [12605758], [], []
Tue Jun 25 12:02:55 CST 2013
Errors in file /home/oracle/orabase/admin/ORACLE/bdump/oracle_q000_3529.trc:
ORA-00600: internal error code, arguments: [2662], [0], [91108810], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108808], [0], [91133612], [12605758], [], []
Tue Jun 25 12:02:56 CST 2013
Errors in file /home/oracle/orabase/admin/ORACLE/bdump/oracle_q000_3529.trc:
ORA-00600: internal error code, arguments: [2662], [0], [91108811], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108810], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108808], [0], [91133612], [12605758], [], []
Tue Jun 25 12:02:57 CST 2013
Errors in file /home/oracle/orabase/admin/ORACLE/bdump/oracle_q000_3529.trc:
ORA-00600: internal error code, arguments: [2662], [0], [91108812], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108811], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108810], [0], [91133612], [12605758], [], []
ORA-00600: internal error code, arguments: [2662], [0], [91108808], [0], [91133612], [12605758], [], []

根据网络资料获取到如下信息：

   ORA-600 [2662] "Block SCN is ahead of Current SCN"，说明当前数据库的数据块的SCN早于当前的SCN，主要是和存储在UGA变量中的dependent SCN进行比较，如果当前的SCN小于它，数据库就会产生这个ORA-600 [2662]的错误了。这个错误一共有五个参数，分别代表不同的含义，

ORA-600 [2662] [a] [b] [c] [d] [e]

Arg [a] Current SCN WRAP

Arg [b] Current SCN BASE

Arg [c] dependent SCN WRAP

Arg [d] dependent SCN BASE

Arg [e] Where present this is the DBA where the dependent SCN came from.

通过查阅文档，发现这个错误的产生原因主要有以下几条：

1.使用隐含参数_ALLOW_RESETLOGS_CORRUPTION后resetlogs打开数据库

2.硬件错误引起数据库没法写控制文件和重做日志文件

3.错误的部分恢复数据库

4.恢复了控制文件但是没有使用recover database using backup controlfile进行恢复

5.数据库crash后设置了_DISABLE_LOGGING隐含参数

6.在并行服务器环境中DLM存在问题

   根据错误中的提示，它的参数b=91108811,d=91133612,表明当前的SCN确实是小于dependent SCN，所以产生了这个600的错误。于是使用ADJUST_SCN事件来调整当前的SCN，使其大于dependent SCN，然后保证数据库可以全库的导出，然后重建数据库导入数据。调整SCN有两种方法：

增进SCN有两种常用方法:
1.通过immediate trace name方式(在数据库Open状态下)
alter session set events 'IMMEDIATE trace name ADJUST_SCN level x';
2.通过10015事件(在数据库无法打开，mount状态下)
alter session set events '10015 trace name adjust_scn level x';
注:level 1为增进SCN 10亿 (1 billion) (1024*1024*1024),通常Level 1已经足够。也可以根据实际情况适当调整。

经询问当班负责人，怀疑为硬件错误引起数据库没法写控制文件和重做日志文件，于是执行如下操作进行恢复打开：

SQL> startup mount
ORACLE instance started.
Total System Global Area   97588504 bytes
Fixed Size                   451864 bytes
Variable Size              33554432 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
SQL> alter session set events '10015 trace name adjust_scn level 1';
Session altered.
SQL> alter database open;
Database altered.
SQL>

然后分别业务账户登录数据库库导出业务数据，重建新库导入业务数据恢复业务。

   参考资料地址：

http://www.eygle.com/archives/2005/12/oracle_diagnostics_howto_deal_2662_error.html

http://www.eygle.com/archives/2005/10/ora00600_2262ii.html

http://www.eygle.com/internal/How.to.Resolve.Ora-600.2662.error.htm