如何解決oracle 11g中的ORA-00845錯誤

oracle11g資料庫，修改了記憶體參數memory_max_target=943718400,關閉資料庫重新啟動的時候報錯

[oracle@instuctor shm]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Mon Nov 19 09:34:11 2012

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup

ORA-00845: MEMORY_TARGET not supported on this system

SQL> exit

Disconnected

[oracle@instuctor shm]$ 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.

查看資料庫的警告日誌，同樣看到了類似的報錯資訊

查看本欄目更多精彩內容：http://www.bianceng.cnhttp://www.bianceng.cn/database/Oracle/

Mon Nov 19 09:34:14 2012

Starting ORACLE instance (normal)

WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 943718400

bytes. /dev/shm is either not mounted or is mounted with available space less than this size. Please fix this so that MEMORY_TARGET can work

as expected. Current available is 845021184 and used is 208900096 bytes. Ensure that the mount point is /dev/shm for this directory.

memory_target needs larger /dev/shm

通過以上原因的分析，看來是/dev/shm剩餘的空間太小了

[oracle@instuctor shm]$ df -H

Filesystem             Size   Used  Avail Use% Mounted on

/dev/sda1               17G    15G   1.2G  93% /

tmpfs                  1.1G   209M   846M  20% /dev/shm

[oracle@instuctor 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，

1.修改初始化參數，使得初始化參數中SGA的設定小於/dev/shm的大小

2.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@instuctor ~]# vi /etc/fstab

LABEL=/                 /                       ext3    defaults        1 1

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

LABEL=SWAP-sda2         swap                    swap    defaults        0 0

~

~

[root@instuctor ~]# mount -o remount /dev/shm

[root@instuctor ~]# df -H

Filesystem             Size   Used  Avail Use% Mounted on

/dev/sda1               17G    15G   1.2G  93% /

tmpfs                  2.2G   209M   2.0G  10% /dev/shm

擴大/dev/shm後，再次嘗試啟動資料庫，沒有問題。

[oracle@instuctor ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Mon Nov 19 10:02:33 2012

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup

ORACLE instance started.

Total System Global Area  939495424 bytes

Fixed Size                  2233960 bytes

Variable Size             616565144 bytes

Database Buffers          314572800 bytes

Redo Buffers                6123520 bytes

Database mounted.

Database opened.