数据库启动报ORA-27154ORA-27300ORA-27301ORA-27302错误

数据库启动报ORA-27154 ORA-27300 ORA-27301 ORA-27302错误

今天同事遇到一个Oracle启动的问题，

sql> startup

ORA-27154: post/wait create failed

ORA-27300: OS system dependentoperation:semget failed with status: 28

ORA-27301: OS failure message: No spaceleft on device

ORA-27302: failure occurred at:sskgpsemsper

[oracle@info bin]$ df -h

Filesystem Size Used Avail Use% Mounted

/dev/sda2 764G 572G 154G 79% /

/dev/sda5 57G 3.5G 51G 7% /home

/dev/sda3 473G 309G 140G 69% /u01

/dev/sda1 190M 25M 156M 14% /boot

tmpfs 32G 17G 16G 52% /dev/shm

检查磁盘，看来不是磁盘空间的问题。

该问题存在与11.2.0.1 之后的版本，，导致的原因是因为semmns 的值太低。 该值在/etc/sysctl.conf中配置。

kernel.sem = semmsl semmns semopm semmni

原来值为：

kernel.sem = 250 32000 100 128

修改值为：

kernel.sem = 256 32768 100 228

修改之后保存退出，之后执行sysctl -p使修改之后的参数生效，之后重启数据库。就OK了。

semaphores 参数的优化原则如下：

1. Calculate the minimum total semaphorerequirements using the following formula:

2*sum (process parameters of all databaseinstances on the system) + overhead for background processes + system and otherapplications.

2. Set semmns (total semaphores systemwide)to this total.

3. Set semmsl (semaphores for each set ) to256

4. Set semmni (total semaphores sets) tosemmns devided by semmsl, rounded up to the nearest multiple of 1024