ORA-00845: MEMORY_TARGET&nb…

主机加了物理内存后，设置MEMORY_TARGET 启动报错

[oracle@pcbames-orcl dbs]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Mon Sep 7 15:56:202015

Copyright (c) 1982, 2009, Oracle.  All rightsreserved.

Connected to an idle instance.

SQL> startuppfile='/u01/app/product/11.2.0/dbhome_1/dbs/init.ora';

ORA-00845: MEMORY_TARGET not supported on this system

SQL> exit

参考：

ORA-00845 Raised When Starting Instance (文档 ID465048.1)转到底部

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In this Document

SymptomsChangesCauseSolutionReferences

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APPLIES TO:

Oracle Database - Enterprise Edition - Version 11.1.0.6 andlater
Oracle Database - Standard Edition - Version 11.2.0.1 to 11.2.0.1[Release 11.2]
Linux x86
Linux x86-64
***Checked for relevance on 30-Sep-2014***

SYMPTOMS

During the startup of the database instance the following erroris raised:

SQL> connect sys as sysdba
Enter password: *****
Connected to an idle instance.

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

The instance alert file shows:

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 atLeast bytes.The /dev/shm is either not mounted or is mounted withavailable space less than this size.
Please fix this so that MEMORY_TARGET can work as expected. Currentavailable is and used is bytes.memory_target needs larger/dev/shm

Also error messages like ORA-4031 may be reported and no newconnections can be established to the database.

CHANGES

The Automatic Memory Management (AMM) has been implemented bysetting parameterslike MEMORY_TARGET and/or MEMORY_MAX_TARGET.

CAUSE

The new Automatic Memory Management functionality uses /dev/shmon Linux for SGA and PGA management. The errors occur if eitherMEMORY_TARGET or MEMORY_MAX_TARGET is configured larger than theconfigured /dev/shm size, or if /dev/shm is mountedincorrectly.

SOLUTION

Please confirm that ORACLE_HOME is set correctly. This errorsometimes happens when it is not set correctly.

Make sure that the /dev/shm size is configured large enough, likein:

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

In this case, the size of the shared memory device is configuredto be 7GB.

In order to make the same change persistent across system reboots,add an entry for this to the /etc/fstab mount table, as in:

shmfs /dev/shm tmpfs size=7g 0

 

Note:

1. You should check with your System Administrator what the "best"size for /dev/shm is, based on what has been reported in the alertfile. 
   
   
2. Also, many best practices now suggest disabling AMM especiallyin Exa* Engineered boxes that have larger memory capability and canuse Huge / Large pages.
   This is because AMM and Huge / Large pages are mutually exclusiveand overall performance will be better using Huge pages

Make sure that the df output shows the correct /dev/shmconfiguration when using Oracle on the system:

$ df -k
Filesystem 1K-blocks Used Available Use% Mounted on
...
shmfs 6291456 832356 5459100 14% /dev/shm