在Oracle数据库启动时提示没有权限 ora-01031:insufficient privileges

环境：Linux

操作语句：

[oracle@ora11r2 ~]$ sqlplus /nolog

SQL*Plus: Release 11.1.0.6.0 - Production on Thu Jun 10 18:22:16 2010

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

SQL> startup                        
ORA-01031: insufficient privileges
SQL> quit
[oracle@ora11r2 ~]$ sqlplus / as sysdba      --得用dba登录才行，汗。。。。。

SQL*Plus: Release 11.1.0.6.0 - Production on Thu Jun 10 18:25:14 2010

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup        
ORACLE instance started.

Total System Global Area  422670336 bytes
Fixed Size                  1300352 bytes
Variable Size             243271808 bytes
Database Buffers          171966464 bytes
Redo Buffers                6131712 bytes
Database mounted.
Database opened.
SQL>