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I have a machine with 10 GB of RAM, and I would like to run Ubuntu on it (Debian also OK if its easier), fully in RAM in such a way: I boot from a compressed image on an USB flash disk, that is uncompressed into RAM, and then I can remove the disk from the USB slot, and use the system only with RAM, without any permanent disk.

Whenever I make any changes that I want permanent, I would put the flash disk back into the USB slot (possibly not the same one as I used initially to boot, as I would like to keep many versions of the boot flash disk), and run some command that would save the current state into a compressed image on the disk.

How can I set this up?

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Heh I asked about this last year but didn't get anywhere. At this rate PCI-E x16 SSDs are going to be here and affordable before I've managed this. – Oli Nov 4 '10 at 13:46
If you are still interested in this look into Casper, or Live-boot. – please delete me Jul 4 '14 at 21:05
Can you confirm that the answer works? – Liam William Sep 3 '15 at 19:21

It is not possible using the Ubuntu desktop CD to do this without keeping the USB disk inserted the entire time. However, given that you have a sufficient amount of RAM, you can use the toram casper option to copy the contents of the desktop CD into memory (by using a tmpfs).

Startup Disk Creator Startup Disk Creator will get you most of the way there. Just be sure to use the "stored in reserved extra space" option. Next, edit syslinux/txt.cfg in the resulting USB disk and put toram just before the -- in every append line except the one for "Check CD for defects."

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Well, aren't live cds doing this already? I use finnix, which is debian based, a lot to do mainteinance, it can boot from CD (or USB), load itself completely into RAM and free the CD slot for use.

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