ORA-00845: MEMORY_TARGET not supported on this system

Problem:-

Database startup throwing error “ORA-00845: MEMORY_TARGET not supported on this system”

SQL> startup nomount;

ORA-00845: MEMORY_TARGET not supported on this system

Observed below error in the Alert log:-

WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 1593835520 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 1326542848 and used is 661401600 bytes. Ensure that the mount point is /dev/shm for this directory.

memory_target needs larger /dev/shm

Solution:-

As per the alert log the error caused is due to the small size allocated to /dev/shm. So I changed the size of /dev/shm to large enough.

As the root user executed below commands:

#mount –t tmpfs shmfs –o size=7G /dev/shm

In this case, the size of the shared memory device is configured to 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:

As root user open /etc/fstab and add below entry

shmfs /dev/shm tmpfs size=7G 0

Note: - If you have RAC setup, perform the above steps in all the nodes.

Now you will be able to start the Oracle instance without above error.