When you need more memory for SGA/PGA when using MEMORY_MAX_TARGET, you need to resize /dev/shm. By default this is 50% of total memory and Oracle tells you to add the following to /etc/fstab:
tmpfs /dev/shm tmpfs defaults,size=3G 0 0
This works after a remount:
mount -o remount /dev/shm
but it doesn’t work after a reboot.
Fix:
add
mount -o remount /dev/shm
in /etc/rc.d/rc.sysinit file at the end and /dev/shm will have attributes from /etc/fstab after reboot.