報錯信息：
[oracle@prac1 dbs]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Mon May 6 13:20:43 2019
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup mount
ORA-00845: MEMORY_TARGET not supported on this system
查看詳細報錯信息：
[oracle@prac2 ~]$ oerr ora 00845
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.
根據報錯信息：
1、MEMORY_TARGET參數不支持該操作系統
2、/dev/shm值設置不正確
解決方法：
修改/dev/shm值。
[root@prac1 ~]# df -h|grep shm
tmpfs 2.0G 686M 1.3G 35% /dev/shm
[root@prac1 ~]# cat /etc/fstab |grep tmpfs
tmpfs /dev/shm tmpfs defaults 0 0
MEMORY_TARGET的值不的等於或大於/dev/shm的值。
修改/dev/shm的值爲3G
[root@prac1 ~]# mount -o remount,size=3G /dev/shm
[root@prac1 ~]# df -h|grep shm
tmpfs 3.0G 686M 2.4G 23% /dev/shm
重新起庫，沒有問題。