Archive for November, 2012

Today I came into the error ORA-00845: MEMORY_TARGET not supported on this system when setting the parameter MEMORY_TARGET on an Oracle instance.

SQL> alter system set memory_target=9G scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system

The solution is to make sure that you have /dev/shm mounted under shmfs. The size should be greater or equal to the size you set MEMORY_TARGET to.

as root:
mount -t tmpfs shmfs -o size=9216m /dev/shm

SQL> startup
ORACLE instance started.

Total System Global Area 9620525056 bytes
Fixed Size 2215704 bytes
Variable Size 4966056168 bytes
Database Buffers 4630511616 bytes
Redo Buffers 21741568 bytes
Database mounted.
Database opened.

Make sure to make an entry in your /etc/fstab to make the changes persistent across reboots.
The entry should be like:
shmfs /dev/shm tmpfs size=9216m 0 0