Resizing Ram disk in Linux (/dev/shm)

mhelm — Wed, 28 Apr 2010 08:52:39 +0000

As many people know linux has a built in ramdisk – this is temporary memory and is very very fast (as it’s in ram). AS standard linux allocates 50% of your ram to this (don’t worry if you don’t use it linux uses all your ram anyway).

However sometimes you may decide the 50% is not enough (or is too much) – especially if the server is upgradeable you may decide you would want to manage the percentage.

Below is an example default entry from /etc/fstab

tmpfs                           /dev/shm        tmpfs   defaults        0 0

This just creates the temporary system using default settings – nothing fancy – however if you want it to take 75% of your ram (or any other percentage) just change it to the code below

- reboot (or remount) and your done.

tmpfs                           /dev/shm                        tmpfs   size=75%                                0 0

How to unmount the tmpfs

umount tmpfs

To remount it with the new settings

mount tmpfs

Michael Helm's Technology Blog » shm

Resizing Ram disk in Linux (/dev/shm)