Oracle ORA-27121 错误解决
Oracle ORA-27121 错误解决，通过冷拷贝(关数据库)的方法对oracle数据库做了迁移，迁移到目标服务器后，在没有把oracle文件的属主
ORA-27121: unable to determine size of shared memory segment
Cause: shmctl() call failed
Action: check permissions on segment, contact Oracle support
问题原因：
通过冷拷贝(关数据库)的方法对oracle数据库做了迁移，迁移到目标服务器后，在没有把oracle文件的属主由root修改为oracle的情况下，执行startup命令，然后报ORA-27121，查看oracle进程，进程都在运行，但是属主是root用户。
根据报警信息和产生报错的环境，推断是由于第一次启动是以oracle用户启动、而文件属主root用户，导致oracle启动实例过程中，进行内存分配时，无法分配导致的。
解决方法：
把已经启动的进程杀掉，，重启系统，oracle实例正常启动。
在CentOS 6.4下安装Oracle 11gR2(x64)
Oracle 11gR2 在VMWare虚拟机中安装步骤
Debian 下 安装 Oracle 11g XE R2
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