ORA-00845: MEMORY_TARGET not supported on this system

oracle启动报错：

ORA-00845: MEMORY_TARGET not supported on this system

进入/opt/oracle/diag/rdbms/orcl/orcl/trace查看alert日志

Mon Aug 14 16:42:56 2017
Adjusting the default value of parameter parallel_max_servers
from 320 to 135 due to the value of parameter processes (150)
Starting ORACLE instance (normal)
WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 27111981056bytes. /dev/shm is either not mounted or is mounted with available space less than this size. Please fix this so that MEMORY_TARGET can work as expected. Current available is17179869184 and used is 0 bytes. Ensure that the mount point is /dev/shm for this directory.
memory_target needs larger /dev/shm
[root@localhost trace]#

要求27111981056字节，实际只有17179869字节，增大共享内存大小，问题解决

mount -t tmpfs shmfs -o size=26g /dev/shm