ORA-00845 Raised When Starting Instance

(Doc ID 465048.1)

Last updated on DECEMBER 18, 2017

Applies to:

Oracle Database - Standard Edition - Version to [Release 11.2]
Oracle Database - Enterprise Edition - Version and later
Linux x86
Linux x86-64


During the startup of the database instance the following error is raised:

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

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 at Least <size> 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 <size> and used is <size> bytes.memory_target needs larger /dev/shm

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


The Automatic Memory Management (AMM) has been implemented by setting parameters like MEMORY_TARGET and/or MEMORY_MAX_TARGET.


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