Booting Ubuntu To RAM
"This article aims to document the process of creating a customized Ubuntu that loads an image from the hard disk to RAM, then boots an entire Ubuntu session out of RAM. It is intended for intermediate to advanced Ubuntu users who are familiar with the shell, and may have limited experience customizing the livecd (LiveCDCustomization) and shell scripting. We will customize a LiveCD and copy it to the hard drive, and make a few modifications to bootup scripts so that it copies to RAM via our good friend tmpfs. [...]
There are many cases where one would like to boot Ubuntu to RAM:
* Performance: The desktop performance is dramatically improved. A 400MB squashed filesystem in RAM, that holds 1200MB of data, is read back on a 1.6GHz Core Duo in about 3 seconds, including decompression time.
* Power, Noise, Durability: Although modern hard disks don't use much power compared to other system components, this may still be important for some. In laptops, hard disks are often the noisiest components, so this setup can reduce system noise. With the hard disk spun down, a laptop can potentially withstand greater shocks without damage.
* Abrupt poweroff: Since the hard disk is only momentarily used in read-only mode during boot, then never touched again, there are few or no negative consequences of an abrupt poweroff. If a system is used where power is inconsistent, or the system is regularly used in a context where fast shutoffs are required, this is very handy.
* Privacy: Anything you do in this session are lost when you reboot or power off. This is great for kiosks or other systems where permanent modification are not desired. (Note that by default the livecd user has full sudo access, so potentially a malicious user can still make permanent changes by mounting the hard drive and following this HOWTO)"