版本：
=========================================
SQL> select * from  v$version;

BANNER
----------------------------------------------------------------
Oracle9i Enterprise Edition Release 9.2.0.6.0 - Production
PL/SQL Release 9.2.0.6.0 - Production
CORE    9.2.0.6.0       Production
TNS for Linux: Version 9.2.0.6.0 - Production
NLSRTL Version 9.2.0.6.0 - Production


启动数据库时，报错
============================================
[oracle@jp11 ~]$ sqlplus '/as sysdba'

SQL*Plus: Release 9.2.0.6.0 - Production on Fri Jul 1 10:00:29 2011

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

Connected to an idle instance.

SQL> startup
ORA-27154: post/wait create failed
ORA-27300: OS system dependent operation:semget failed with status: 28
ORA-27301: OS failure message: No space left on device
ORA-27302: failure occurred at: sskgpcreates

检查磁盘空间使用情况：
====================================
[oracle@jp11 ~]$ df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2             20161204  19137320         0 100% /
/dev/sda1               101086     12168     83699  13% /boot
none                   1032036         0   1032036   0% /dev/shm
/dev/sda5            131514912 110213232  14621052  93% /opt

删除了/opt和/下的一些文件，空间情况：
======================================
[root@jp11 oracle]# df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2             20161204  10815588   8321476  57% /
/dev/sda1               101086     12168     83699  13% /boot
none                   1032036         0   1032036   0% /dev/shm
/dev/sda5            131514912 110173872  14660412  89% /opt
[root@jp11 oracle]#

尝试打开数据库：
==================
[oracle@jp11 ~]$ sqlplus '/as sysdba'

SQL*Plus: Release 9.2.0.6.0 - Production on Fri Jul 1 10:00:29 2011

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

Connected to an idle instance.

SQL> startup  ====>空间确保后，打开仍然失败
ORA-27154: post/wait create failed
ORA-27300: OS system dependent operation:semget failed with status: 28
ORA-27301: OS failure message: No space left on device
ORA-27302: failure occurred at: sskgpcreates


针对ORA-27154错误，网上搜索了一下，进行了如下处理
=================================================
[oracle@jp11 ~]$ cat /proc/sys/kernel/sem
100     256     100     100
[oracle@jp11 ~]$
[oracle@jp11 ~]$ su
Password:
[root@jp11 oracle]#
[root@jp11 oracle]# echo "110  10000 110 128" > /proc/sys/kernel/sem
[root@jp11 oracle]# cat /proc/sys/kernel/sem
110     10000   110     128
[root@jp11 oracle]#


==========================

SQL> startup
ORACLE instance started.

Total System Global Area  581506668 bytes
Fixed Size                   452204 bytes
Variable Size             402653184 bytes
Database Buffers          167772160 bytes
Redo Buffers               10629120 bytes
Datebase mounted.
Database opend.
SQL>
SQL> select status from v$instance;

STATUS
------------
OPEN


=========================================
[oracle@jp11 ~]$ cat /proc/sys/kernel/sem
100     256     100     100

以上4个数据分别对应
SEMMSL  SEMMNS  SEMOPM  SEMMNI

SEMMSL         100        Defines the minimum recommended value,
                           for initial installation only

SEMMNS         256         Defines the maximum semaphores on the system.
                           This setting is a minimum recommended value,
                           for initial installation only. The SEMMNS parameter
                           should be set to the sum of the PROCESSES parameter
                           for each Oracle database, adding the largest one twice,
                           and then adding an additional 10 for each database.

SEMOPM         100         Defines the maximum number of operations for each semop call

SEMMNI         100         Defines the maximum number of semaphore sets in the entire system