在radhat5的Oralce11：startup时报错：
1 | SQL> startup |
显示：
ORA-00845: MEMORY_TARGET not supported on this system
来自Oracle的官方解析是：
Starting with Oracle Database 11g, the Automatic Memory Management feature requires more shared memory (/dev/shm)and file descriptors. The size of the shared memory should be at least the greater of MEMORY_MAX_TARGET and MEMORY_TARGET for each Oracle instance on the computer. If MEMORY_MAX_TARGET or MEMORY_TARGET is set to a non zero value, and an incorrect size is assigned to the shared memory, it will result in an ORA-00845 error at startup.
打开终端：
1 | df -h | grep shm |
显示：
tmpfs 2.0G 0 2.0G 0% /dev/shm
修改一下tmpfs值，将2G修改大点。
打开终端：
1 | cp /etc/fstab /etc/fstab_back |
修改内容：
tmpfs /dev/shm tmpfs defaults,size=16G 0 0
通过重启使这个配置生效
