打开虚拟机发现实例起不来

[root@wenxi ~]# su - oracle
sq[oracle@wenxi ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Tue Aug 2 14:59:54 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

SYS@ odb>startup nomout
SP2-0714: invalid combination of STARTUP options

[oracle@wenxi ~]$ oerr ora 000845
00845, 00000, "MEMORY_TARGET not supported on this system"
// *Cause: The MEMORY_TARGET parameter was not supported on this operating system or /dev/shm was not sized correctly on Linux.
// *Action: Refer to documentation for a list of supported operating systems. Or, size /dev/shm to be at least the SGA_MAX_SIZE on each Oracle instance running on the system.

在oracle 11g中新增的内存自动管理的参数MEMORY_TARGET,它能自动调整SGA和PGA，这个特性需要用到/dev/shm共享文件系统，而且要求 /dev/shm必须大于MEMORY_TARGET，如果/dev/shm比MEMORY_TARGET小就会报错

[oracle@wenxi ~]$ df -h /dev/shm/
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           1.5G   72K  1.5G   1% /dev/shm

*.memory_target=1603272704     约为1.6G

解决办法是加大/dev/shm的空间

[oracle@wenxi ~]$  cat /etc/fstab | grep tmpfs
tmpfs                   /dev/shm                tmpfs   defaults        0 0

[root@wenxi ~]#  mount -o remount,size=2G /dev/shm

[root@wenxi ~]# df -h /dev/shm/
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           2.0G   72K  2.0G   1% /dev/shm

[root@wenxi ~]# vim /etc/fstab

tmpfs                   /dev/shm                tmpfs   defaults,size=2G

正常打开了

SYS@ odb>startup
ORACLE instance started.

Total System Global Area 1603411968 bytes
Fixed Size                  2253664 bytes
Variable Size             989858976 bytes
Database Buffers          603979776 bytes
Redo Buffers                7319552 bytes
Database mounted.
Database opened.