Oracle 11g的Linux版本在修改了MEMORY_TARGET或者SGA_TARGET后启动可能会报错：

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup

ORA-00845: MEMORY_TARGET not supported on this system

这个问题是由于设置SGA的大小超过了操作系统/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的文档：Doc ID: Note:460506.1中进行了说明。解决这个问题只有两个方法，一种是修改初始化参

数，使得初始化参数中SGA的设置小于/dev/shm的大小，另一种方法就是调整/dev/shm的大小。

修改/dev/shm的大小可以通过修改/etc/fstab来实现：

[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

[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，然后就可以启动数据库了。

相关metalink 文章 ：

ORA-00845 When Starting Up An 11g Instance With AMM Configured. [ID 460506.1]

Applies to:

Oracle Server - Enterprise Edition - Version: 11.1.0.6 to 11.2.0.2.0 - Release: 11.1 to 11.2

Linux x86

Linux x86-64

Symptoms

On a Linux system, trying to start up an 11g instance could fail with the following error:

ORA-845: MEMORY_TARGET not supported on this system

In the alert log, you could or could not see the below messages:

ORA-04031 errors

OR

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 bytes.The /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 and used is bytes.memory_target needs larger /dev/shm

If ORA-04031 is seen in the alert log, sometimes you can not establish new connections due to this

problem.

Changes

Installed 11g, or created a new database on 11g and is starting to use the AMM (Automatic Memory

Management) feature.

Cause

This feature requires the /dev/shm file system to be mounted for at least %llu bytes.

/dev/shm is either not mounted or is mounted with available space less than this size.

Explanation:

AMM (Automatic Memory Management) is a new feature in 11 which manages both SGA and PGA.

MEMORY_TARGET is used instead of SGA_TARGET and MEMORY_MAX_TARGET is used instead of SGA_MAX_SIZE

(defaults to MEMORY_TARGET ).

It uses /dev/shm on Linux. If max_target set over /dev/shm size, you get the error messages.

Solution

1. If you are installing Oracle 11g on a Linux system, note that Memory Size (SGA and PGA), which sets

the initialization parameter MEMORY_TARGET or MEMORY_MAX_TARGET, cannot be greater than the shared

memory filesystem (/dev/shm) on your operating system. To resolve the current error, increase the

/dev/shm file size. For example:

# mount -t tmpfs shmfs -o size=7g /dev/shm

Also, to make this change persistent across system restarts, add an entry in /etc/fstab similar to the

following:

shmfs /dev/shm tmpfs size=7g 0

2. This error may also occur if /dev/shm is not properly mounted. Make sure your df output is similar to

the following:

$ df -k

Filesystem 1K-blocks Used Available Use% Mounted on

...

shmfs 6291456 832356 5459100 14% /dev/shm

3. If configuring AMM is not possible due to lack of space on /dev/shm mount point, you can configure

ASMM instead of AMM, i.e. set SGA_TARGET, SGA_MAX_SIZE and PGA_AGGREGATE_TARGET instead of

MEMORY_TARGET.

References

NOTE:752899.1 - /dev/shm Filled Up With Files In Format JOXSHM_EXT_xxx_SID_xxx

相关的

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产品

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Oracle Database Products > Oracle Database > Oracle Database > Oracle Server - Enterprise Edition

关键字

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MEMORY_TARGET; START INSTANCE

错误

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ORA-4031; ORA-845; 04031 ERROR