[oracle@up ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Tue Nov 10 19:26:05 2015
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORA-00845: MEMORY_TARGET not supported on this system
SQL>
错误原因：tmpfs空间不能小于MEMORY_TARGET的值，tmpfs空间太小数据库无法启动
[root@up ~]# vi /u01/app/oracle/product/11.2.0/dbs/init.ora
db_name=‘ORCL‘
memory_target=1G
processes = 150
audit_file_dest=‘<ORACLE_BASE>/admin/orcl/adump‘
audit_trail =‘db‘
db_block_size=8192
db_domain=‘‘
数据库参数文件里memory_target参数的大小为1G
[root@up ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 26G 17G 7.4G 70% /
tmpfs 242M 0 242M 0% /dev/shm
/dev/sda1 190M 28M 153M 16% /boot
tmpfs空间大小242M，所以无法启动数据库
解决方法，在/etc/fstab里修改tmpfs的挂载选项，增大tmpfs的空间
[root@up ~]# vi /etc/fstab
UUID=a6948461-a0e3-4e64-bf75-e9a45864d48a / ext4 defaults 1 1
UUID=0d5a41b3-3988-467f-be75-93e0e4fad1e9 /boot ext4 defaults 1 2
UUID=bba460fd-bdbe-4a7e-ba49-4016f4633067 swap swap defaults 0 0
tmpfs /dev/shm tmpfs defaults,size=2G 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
修改tmpfs挂载，将tmpfs空间大小设置为2G
重启系统
[root@up ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 26G 17G 7.4G 70% /
tmpfs 2.0G 0 2.0G 0% /dev/shm
/dev/sda1 190M 28M 153M 16% /boot
更改后tmpfs为2G
[root@up ~]# su - oracle
[oracle@up ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Tue Nov 10 19:40:28 2015
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 409194496 bytes
Fixed Size 2213856 bytes
Variable Size 301991968 bytes
Database Buffers 96468992 bytes
Redo Buffers 8519680 bytes
Database mounted.
Database opened.
问题解决，数据库启动完毕
原文地址：http://8469401.blog.51cto.com/8459401/1711345
