ORA-00845: MEMORY_TARGET not supported on this system

MEMORY_TARGET not supported on this system

Applies to:

            Oracle Enterprise Linux – Version: 5

            Oracle Database 11gR2

Description:

            I am going to create a new TEST instance from Production database. Hardware resources on TEST server less than from Production server. After restore the backup when I am going to start the database I got the following error message:

SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup;
ORA-00845: MEMORY_TARGET not supported on this system

Solution:

After some research work I have found the following solution:

• Check out /dev/shm is properly mounted by using following commands:
  #df -h or #df -k command
• Size of /dev/shm should be greater than MEMORY_TARGET or MEMMORY_MAX_TARGET parameter value
• We see that /dev/shm have assigned 2G memory, and MEMORY_TARGET more than 2G then above ORA-845 will arise.
• If you have MEMORY_TARGET or MEMORY_MAX_TARGET set to 4G then you should mount shared memory to greater than 4G.
• Now login to root user and execute the following commands to fix the error:

# umount tmpfs
# mount -t tmpfs shmfs -o size=5G /dev/shm

• In order to make the settings persistence you should add an entry in /etc/fstab similar to the following:
  shmfs /dev/shm tmpfs size=5G 0

Your comments, especially which will help us improve the functionality, will be greatly appreciatedJ