Is there a way to tell the system to keep a folder to reside in memory?

Question

I'm developing a Java EE web application and I'm trying to speed up the testing process. To do so I was wondering if there is a way to tell the system to keep my build folder in system memory?

Answer 1

Yes. You can put the folder in a RAM disk.

I would write up instructions, but a lot of people have already done good jobs at that, like the guy that wrote http://blulin.wordpress.com/2008/11/28/tips-to-create-ramdisk-in-a-linux-system/

Keep your source and work in a folder on a hard disk, and when you're going to test, just rsync that directory to the ramdisk you're going to create using the page i linked to.

Do all your testing.

Save all your work back to your folder on the hard disk.

Voila!

ps. That "Save your work" step is a must. When you unmount a ramdisk, everything is gone. there is no such thing as a ram disk that provides persistent storage.

Answer 2

Normally the system puts everything into cache as long there is free memory available, so normally this step does not seem to be necessary.

Check if there is a /dev/shm mountpoint. On most distributions halve of your RAM is mounted there as ramdisk.

Answer 3

You can use tmpfs.

tmpfs is a fast, dynamically allocated, easy to use, temporary file storage facility, that will swap to disk when you run out of memory. Although a ramdisk has some advantages in other use cases, tmpfs will suit your needs best.

For one time use:

sudo mount -t tmpfs none /path/to/directory

When you want to mount the directory as tmpfs everytime you boot, append the following to /etc/fstab:

none /path/to/directory tmpfs defaults 0 0

Warning: Everything you write into your tmpfs directory will be lost on shutdown, so save or rsync everything when you are done.