ORA-27300: OS system dependent operation:semget failed with status: 28 - 2

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本文介绍了解决Linux环境下Oracle数据库启动时遇到ORA-27300错误的方法。该错误通常与系统可用信号量资源不足有关。文章详细分析了信号量配置与使用情况，并提供了解决方案，包括调整内核参数SEMMNI。

Database Startup Fails with ORA-27300: OS system dependent operation:semget failed with status: 28 (文档 ID 949468.1)

Oracle Database - Enterprise Edition - Version 10.1.0.2 to 11.2.0.2 [Release 10.1 to 11.2]
Information in this document applies to any platform.

SYMPTOMS
On a linux server, when an additional database instance is brought up, getting errors:
SQL> startup nomount
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

CHANGES
An additional database has been created on a linux server.
PROCESSES parameter in init.ora set to the correct value, accordingly.
Linux Kernel Parameter for Semaphore - Total 32000 semaphore are available in the system but still gets an error - ORA-27300.
$ ipcs -ls

------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 100
semaphore max value = 32767

CAUSE
In theory, 32000 semaphores are available in the system and one semaphore identifier can accommodate a maximum of 250 semaphores with
the configuration above.
But ipcs command shows each semaphore identifier accomodates maximum of 156 semaphores by Oracle.

$ ipcs << For this case, it has around 100 semaphore identifiers being used without bringing up the additional instance.
..

------ Semaphore Arrays --------
key semid owner perms nsems
0x450e15bd 0 root 666 1
0x0000cace 32769 root 666 1
0x358b172c 327683 oracle 660 104
0x9053d038 11075588 oracle 660 156
0x9053d039 11108357 oracle 660 156
0x9053d03a 11141126 oracle 660 156
0x9053d03b 11173895 oracle 660 156
..
According to this figure, the maximum available semaphores in this server will be 156 x 128 = 19968, not 32000.

SOLUTION
SEMMNI should be increased to accomodate more semaphores.

1. Query the current semaphore values in the kernel
# /sbin/sysctl -a | grep sem

2. Modify SEMMNI value in the /etc/sysctl.conf.
From
kernel.sem = 250 32000 100 128
To
kernel.sem = 250 32000 100 200

3. # /sbin/sysctl -p

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