Oracle 11.2.0.1 on Linux
I wish to configure a database to use Automatic Memory Management (AMM). According to the Oracle manual (Oracle Database Preinstallation Tasks), the amount of memory available is limited by the size of the shared memory mount /dev/shm.
The size of the shared memory must be at least the greater of the MEMORY_MAX_TARGET and MEMORY_TARGET parameters for each Oracle instance on the computer.
My Linux server has 24GB of physical RAM, but the shared memory mount /dev/shm is only 12GB (I'm guessing the default is 50% of RAM). As a result, I am unable to assign more than 12GB of memory to Oracle using AMM. If MEMORY_MAX_TARGET is set greater than 12GB, the database will not start. Nothing else is running on the server, and I would like to allocate more than 12GB of memory to Oracle.
Are there any recommended limits on sizing /dev/shm in this situation, or can it simply be increased to something closer to 80-100% of physical RAM to make more memory available to Oracle as required. Are there any drawbacks to making /dev/shm this large?