[Novalug] basic Q's about flash boot of live CD

Peter Larsen plarsen@famlarsen.homelinux.com
Tue Mar 23 22:00:42 EDT 2010


On Tue, 2010-03-23 at 10:47 +0000, Bryan J Smith wrote:
> I wasn't aware you could run "yum update" on the Live USB either.
> I thought you had to completely rebuild the Live USB, because
> it too is an immutable Squashfs. So either you're missing my point,
> or I'm more ignorant of recent changes.

Yup - it's one of the very very NICE things with the live USB. You can
add software and even update your image. Yes, you're not touching the
original image, but it's just a block overlay for the change. It's very
quick and doesn't have much of an overhead.

> Stateless is stateless. It defines what directories are immutable
> and what directories are temporary/persistent. Again, I do not
> believe you are correct when you say you can run "yum update"
> on a Live USB boot.  But I haven't tried the latest Fedora Live USB
> either. But I'm fairly certain this is the design.

F11 did the same thing. And I remember doing a few beta-tests on F10
with the same features. 

> To change the binaries you still need to completely rebuild the image,
> regardless of the media.  

Nope!

> I'll take the time to build a Live USB
> myself from the latest Fedora 12 in the next few days to confirm
> this is how it still works. Because unless stateless has changed
> radically, and lets you overlay anything and everything without
> radical reconfiguration, your statements (based on testing?
> or assumption?) sound wholly incorrect from how I have known
> stateless to work with the Fedora initrd-init through at least
> Fedora 10.

Based on actual use. At FOSE2009 I brought about 100 USB sticks with
live F10 on them. They all had this feature.


> That's why I say there is no difference between Live CD and Live
> USB, except for the fact that you can write a few directories
> to the Live USB - but a yum doesn't sound like its possible.

You're confusing the concepts a bit. It's not writing back to the
persistent read/only image. It's writing back to a "delta" which is on a
separate part of the USB stick. When you create your stick, you define
the size of this area (overlay) and it's used to store the changes you
make.

-- 
Best Regards
  Peter Larsen

Wise words of the day:
And now for something completely different.
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