【问题记录】数据库打不开 报ORA-00845错误 /dev/shm设置过小

--startup时报错

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

 

--查看该错

[oracle11@CD1 goldengate]$ oerr ora 845
00845, 00000,"MEMORY_TARGET not supported on this system"
// *Cause: TheMEMORY_TARGET parameter was not supported on this operating system or /dev/shmwas 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 oneach 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（SGA_MAX_SIZE），如果/dev/shm比MEMORY_TARGET小就会报错。

 

--查看当前/dev/shm大小

[oracle11@CD1 goldengate]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       26G   16G 8.6G  65% /
/dev/sda1              99M   13M  82M  14% /boot
tmpfs                
624M     0 624M   0% /dev/shm

 

--将/dev/shm调大

[root@CD1 ~]# cat /etc/fstab | grep tmpfs
tmpfs                   /dev/shm                tmpfs  defaults        0 0
 
[root@CD1 ~]# mount -o remount,size=1g /dev/shm
 

 

--确保操作系统重启之后能生效，修改/etc/fstab文件

[root@CD1 ~]# cat /etc/fstab | grep tmpfs
tmpfs                   /dev/shm                tmpfs   defaults        0 0
 
[root@CD1 ~]# vi /etc/fstab
/dev/VolGroup00/LogVol00/                       ext3    defaults        1 1
LABEL=/boot             /boot                   ext3    defaults        1 2
tmpfs                  /dev/shm                tmpfs   defaults,size=1g       0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/VolGroup00/LogVol01swap                    swap    defaults        0 0

 

--确认修改结果

[root@CD1 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                       26G   16G 8.6G  65% /
/dev/sda1              99M   13M  82M  14% /boot
tmpfs                
1.0G     0 1.0G   0% /dev/shm

 

--打开数据库

[root@CD1 ~]# su - oracle11
[oracle11@CD1 ~]$ sql
 
SQL*Plus:Release 11.2.0.3.0 Production on Wed Dec 25 13:18:48 2013
 
Copyright (c)1982, 2011, Oracle.  All rights reserved.
 
Connected toan idle instance.
 
SQL> startup
ORACLEinstance started.
 
Total SystemGlobal Area  839282688 bytes
FixedSize                  2233000 bytes
VariableSize             511708504 bytes
DatabaseBuffers          318767104 bytes
RedoBuffers                6574080 bytes
Databasemounted.
Databaseopened.
成功打开了！

 

--查看memory_target参数

SQL> show parameter memory_target
 
NAME                  TYPE                          VALUE
--------------------------------------------------------------------- ------------------------------
memory_target           big integer                
804M
 
SQL> show parameter SGA_MAX_SIZE
 
NAME                  TYPE                 VALUE
--------------------------------------------------------------------- ------------------------------
sga_max_size            big integer            
804M

原先的/dev/shm 为624M，小于804M，因此数据库不能打开！