Starting with Oracle Database 11g, the Automatic Memory Management feature requires more shared memory (/dev/shm)and file descriptors. The size of the shared memory should be at least the greater of MEMORY_MAX_TARGET and MEMORY_TARGET for each Oracle instance on the computer. If MEMORY_MAX_TARGET or MEMORY_TARGET is set to a non zero value, and an incorrect size is assigned to the shared memory, it will result in an ORA-00845 error at startup.

 即 MEMORY_MAX_TARGET 的设置不能超过 /dev/shm 的大小：

加大：

2、SQL> startup nomount
ORA-09925: Unable to create audit trail file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 9925

SQL> quit

SQL> sqlplus / as sysdbaSQL*Plus: Release 11.2.0.1.0 Production on Wed Apr 1 21:13:17 2015

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

ERROR:
ORA-09925: Unable to create audit trail file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 9925
ORA-01075: you are currently logged on

Enter user-name: 

这下sys用户登录也报这个错

查看参数文件 initENMOEDU1.ora

发现audit_file_dest='/u01/app/oracle/admin/orcl/adump'

在创建参数文件时，审计文件路径居然是默认的，没有改为之前创建好的路径，并且默认路径并没有创建好

解决办法：

mkdir -p /u01/app/oracle/admin/orcl/adump    -- 创建之前错误的没有创建好的路径

  [oracle@rhel6 dbs]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Wed Apr 1 21:39:16 2015

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> 

此时超级用户正常登录

修改参数文件initENMOEDU1.ora

将审计文件路径按规律改写为 audit_file_dest='/u01/app/oracle/admin/ENMOEDU1/adump'

重新创建二进制参数文件报错

SQL> create spfile from pfile;
create spfile from pfile
*
ERROR at line 1:
ORA-32002: cannot create SPFILE already being used by the instance

解决：SQL> shu immediate
ORA-01507: database not mounted


ORACLE instance shut down.

SQL> create spfile from pfile;

File created.SQL> startup nomount
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size            2220200 bytes
Variable Size          616566616 bytes
Database Buffers      444596224 bytes
Redo Buffers            5554176 bytes

3、

SQL> alter database mount
  2  ;
alter database mount
*
ERROR at line 1:
ORA-00205: error in identifying control file, check alert log for more info

nomount状态成功，mount报错，找不到控制文件

原因：未创建database，即未执行create database 语句

SQL> @/home/oracle/Desktop/oracle/create_db/create_db

Database created.

SQL> alter database mount;
alter database mount
*
ERROR at line 1:
ORA-01100: database already mounted

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01531: a database already open by the instance

意思是在执行完创建数据库语句之后自动完成mount和open操作

之后按步骤创建数据库顺利完成。