Oracle Diag:如何处理ORA-600 2662错误

在ORA-00600 2262错误解决一文中，我曾经提到过，很多时候使用隐含参数_ALLOW_RESETLOGS_CORRUPTION后resetlogs打开数据库,我们可能会由于SCN不一致而遭遇到ORA-00600 2662号错误，这里给出一个完整的例子及解决过程。

当然模拟2662错误需要技巧，本文并不会涉及这个内容。

通过正常方式启动数据库时，从alert文件中，我们可以看到ora-00600 2662号错误。

Sun Dec 11 18:02:25 2005
Errors in file /opt/oracle/admin/conner/udump/conner_ora_13349.trc:
ORA-00600: internal error code, arguments: [2662], [0], [547743994], [0], [898092653], [8388617], [], []
Sun Dec 11 18:02:27 2005
Errors in file /opt/oracle/admin/conner/udump/conner_ora_13349.trc:
ORA-00600: internal error code, arguments: [2662], [0], [547743994], [0], [898092653], [8388617], [], []
Sun Dec 11 18:02:27 2005
Error 600 happened during db open, shutting down database
USER: terminating instance due to error 600

此时我们可以通过Oracle的内部事件来调整SCN:

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。

本例由于数据库无法打开，只能使用的二种方法。

[oracle@jumper dbs]$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on Sun Dec 11 18:26:18 2005

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to an idle instance.

SQL> startup mount pfile=initconner.ora
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 10';

Session altered.

SQL> alter database open;

Database altered.

注意,由于我使用了10015事件，使得SCN增进了10 billion，稍后我们可以验证。 

[oracle@jumper dbs]$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on Sun Dec 11 18:26:18 2005

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to an idle instance.

SQL> startup mount pfile=initconner.ora
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 10';

Session altered.

SQL> alter database open;

Database altered.

此时数据库可以打开，从alert文件中我们可以看到如下提示:

Sun Dec 11 18:27:04 2005
SMON: enabling cache recovery
Sun Dec 11 18:27:05 2005
Debugging event used to advance scn to 10737418240

SCN被增进了10 billion,即 10 * (1024*1024*1024) = 10737418240,正好是日志里记录的数量。