Oracle常見錯誤——ORA-00845

Oracle 11g的Linux版本在修改了MEMORY_TARGET或者SGA_TARGET後啓動可能會報錯：

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system

 

 

這個問題是由於設置SGA的大小超過了操作系統/dev/shm的大小：

[root@enterprice64 ~]# df -k /dev/shm
Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 4089416 0 4089416 0% /dev/shm

Oracle在metalink的文檔：Doc ID: Note:460506.1中進行了說明。解決這個問題只有兩個方法，一種是修改初始化參數，使得初始化參數中SGA的設置小於/dev/shm的大小，另一種方法就是調整/dev/shm的大小。

修改/dev/shm的大小可以通過修改/etc/fstab來實現：

[root@enterprice64 ~]# vi /etc/fstab

LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
LABEL=/data /data ext3 defaults 1 2
devpts /dev/pts devpts gid=5,mode=620 0 0
#tmpfs /dev/shm tmpfs defaults 0 0
tmpfs /dev/shm tmpfs defaults,size=10240M 0 0
LABEL=/home /home ext3 defaults 1 2
LABEL=/opt /opt ext3 defaults 1 2
proc /proc proc defaults 0 0
sysfs /sys sysfs defaults 0 0
LABEL=/usr /usr ext3 defaults 1 2
LABEL=/var /var ext3 defaults 1 2
LABEL=SWAP-sda8 swap swap defaults 0 0
~
~
"/etc/fstab" 13L, 965C written
[root@enterprice64 ~]# umount /dev/shm
[root@enterprice64 ~]# mount /dev/shm
[root@enterprice64 ~]# df -k /dev/shm
Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 10485760 0 10485760 0% /dev/shm
[root@enterprice64 ~]# su - oracle
[oracle@enterprice64 ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 11.1.0.6.0 - Production on Tue Oct 23 15:42:42 2007

Copyright (c) 1982, 2007, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area 4743446528 bytes
Fixed Size 2143824 bytes
Variable Size 3892316592 bytes
Database Buffers 805306368 bytes
Redo Buffers 43679744 bytes
Database mounted.
Database opened.

修改/etc/fstab，重新mount /dev/shm，然後就可以啓動數據庫了。