oracle11gR2：

SQL> startup nomount
ORA-00845: MEMORY_TARGET not supported on this system

告警日志：

WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 788529152 bytes. /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 is 517730304 and used is 464449536 bytes. Ensure that the mount point is /dev/shm for this directory.
memory_target needs larger /dev/shm

google：

11g特性的内存管理需要用到/dev/shm共享文件系统，且要求/dev/shm大于 TARGET_MEMORY，否则会报错。

[root@mosdb ~]# mount -t tmpfs shmfs -o size=3g /dev/shm
[root@mosdb ~]#

写入到fstab中：

vi /etc/fstab 增加如下：

shm /dev/shm tmpfs size=2g 0 0

#mount shm

[root@mosdb etc]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
37G 17G 18G 49% /
/dev/sda1 99M 13M 81M 14% /boot
shm 2.0G 0 2.0G 0% /dev/shm

在启动数据库：（可见内存加载成功）
SQL> startup nomount;
ORACLE instance started.

Total System Global Area 786759680 bytes
Fixed Size 1339400 bytes
Variable Size 528486392 bytes
Database Buffers 251658240 bytes
Redo Buffers 5275648 bytes
SQL>

[@more@]