本文主要向大家介绍了Oracle数据库之RHEL 7.2 ORA-27300 ORA-27301  Database Crash，通过具体的内容向大家展现，希望对大家学习Oracle数据库有所帮助。

一、环境描述：
操作系统RHEL 7.2
数据库ORACLE 12.2.0.1 
生产系统

二、官方文档解决方法

APPLIES TO:
Oracle Database - Enterprise Edition - Version 9.2.0.1 and later
Information in this document applies to any platform.
***Checked for relevance on 29-Jun-2012***
SYMPTOMS
Database instance crashed due to following errors:

ORA-27300: OS system dependent operation:semctl failed with status: 22
ORA-27301: OS failure message: Invalid argument
ORA-27302: failure occurred at: sskgpwrm1
ORA-27157: OS post/wait facility removed
ORA-27300: OS system dependent operation:semop failed with status: 36
ORA-27301: OS failure message: Identifier removed
ORA-27302: failure occurred at: sskgpwwait1

CAUSE
The semaphores used by Oracle have been inadvertendly removed

The errors are signalling that something happened at the OS level with shared memory and/or semaphores. The semaphore sets could be removed manually, or they could be dying for some reason due to a hardware error.

Either when remounting the /dev/shm or You may want to check for any possibility of a user dba using the "ipcrm" command to kill the semaphores (accidentally) since the error ora-27301 (OS failure message: Identifier removed) suggests that. Also, it could have been a bad memory stick or something else at the OS level. Someone could also have removed the shared memory segments at the OS level for some specific reason, or by accident. Most likely something had removed the shared memory and semaphore sets in use by 'oracle'. This can only be done by a root-level user or 'oracle' itself who owns the resources. If someone logged in as root and removed all IPC resources, Oracle would crash when it lost the allocated shared memory/semaphores.

Note: This issue can happen on different platform, but in case you encounter the issue in RHEL7.2, then please also check below RHEL7.2 specific information.
In  RHEL7.2 operating system setting RemoveIPC=YES crashes the database.The default value for RemoveIPC in RHEL7.2 is YES.

         Workaround :

      1) Set RemoveIPC=no in /etc/systemd/logind.conf if it is not in that file

      2) Reboot the server or restart systemd-logind as follows:
       # systemctl daemon-reload
       # systemctl restart systemd-logind

         OR

       Migrate to Oracle Linux 7.2 resolves the problem.

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