[Fedora-livecd-list] RFC- 'persistance' is on LiveCD wishlist - what does it mean?

[Jeremy Katz]

On Mon, 2007-07-16 at 16:03 -0500, Douglas McClendon wrote:
> While I have plenty of ideas for this, and have vague memories of seeing other 
> distributions do it, I'd like to get a feel for what the fedora community 
> actually wants.  I.e. lets design this feature.  How should it work from the end 
> user perspective?

The crux of the idea is that you have a file on some form of read/write
device that can store changes that you've made to the system.  So, eg,
if I boot with the live image (either off of CD or a usb key) and
install emacs because I can't use a system without emacs, those changes
are saved and the next time I boot, I have my emacs installed already.  

The simple and obvious way to do this is to be able to look for a file
with a certain name (based on a UUID from the live image) located on
either a USB key or a hard drive and then layer that as our snapshot dev
rather than a sparse file in memory.  That then leaves a few questions:

1) Do we then mount every partition we can find in the initramfs to get
to the persistence file (with an option to disable, obviously)?  Or do
we require the device info to be specified in the bootloader.  The first
has the advantage of more "just working".  The second is better for the
case of not touching things and thus being a little bit safer. 

2) How do we do the initial set up of this file?  It's easy enough once
they've booted the image to say "set up a persistence file for future
use" and be able to prompt for where to keep it, etc.  But then do we
try to snapshot to it immediately and save any changes they've already
made?  Obviously this is better from a user perspective, but may be
tricky to do sanely

3) When doing an install from the live image, do we keep the changes?
If so, how does that interact with some of the hacky things we currently
do in the live init script such as user addition and disabling
firstboot?

I somewhat suspect that the answer is to get together the quick path for
each of these (explicit specification of where the persistence is,
require manual set up) and just see how things work.

Jeremy