[Fedora-livecd-list] Fwd: Migrating persistent overlay into the squashfs

[Frederick Grose]

Forwarded conversation
Subject: [Fedora-livecd-list] Migrating persistent overlay into the squashfs
------------------------

From: *James Heather* <j.heather(a)surrey.ac.uk&gt;
Date: Fri, Jul 22, 2011 at 3:43 AM
To: livecd(a)lists.fedoraproject.org


**
I have a feeling that someone recently wrote something to allow you to
migrate changes from the persistent overlay into the squashfs image, thus
freeing up the space in the overlay. The obvious use case is:


   1. Boot live USB stick
   2. yum update (which will eat up lots of overlay space)
   3. Run whatever it is, from a separate system, to recreate the squashfs
   image to take account of the changes (freeing up the overlay space again)


But I can't find it. It doesn't seem to be in liveimage-mount. Did whatever
it was make it into F15? If not, does anyone know what it is, where it is,
how to use it, and whether it works?

Thanks.

James

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From: *Alan Pevec* <apevec(a)gmail.com&gt;
Date: Fri, Jul 22, 2011 at 4:42 AM
To: livecd(a)lists.fedoraproject.org


Interesting idea, I don't remember it being discussed here but
edit-livecd change in commit c41b33bf4f59c35fc9cf8fd8dd6933cf142e8f0c
introduced something similar: it allows you to clone running livecd
system into a fresh iso.

The idea could be extended to work off-line too: open
iso->squashfs->rootfs, add overlay (basically copy/paste from dracut
dmsquash-live module) and copy result to the new rootfs.

Alan
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------------------------


I am working on that project.  The patches are attached to this ticket,
https://bugzilla.redhat.com/show_bug.cgi?id=448030

A regression in rsync support for xattributes upset the development and
testing plan for Fedora 15.  See this post,
http://lists.fedoraproject.org/pipermail/livecd/2011-April/006736.html

However, in the mean time I have developed a version that uses the
device-mapper mirror service to perform the copy (instead of rsync), and by
switching dm tables under the root filesystem, it refreshs a live or
attached image to the rebuilt image.

I have been developing and testing with a Fedora 15 Live image, and it
works.  I'll post another alpha version of the latest developments in a few
days.

(Just last night, I updated this page in our wiki,
http://wiki.sugarlabs.org/go/LiveOS_image
adding the last 2 sections.
The project page is
http://wiki.sugarlabs.org/go/Sugar_on_a_Stick/Sugar_Clone
although it doesn't reflect the latest developments.)

Endurance of a LiveUSB image is particularly significant to Sugar on a Stick
because it is unique among the Fedora Spins
http://spins.fedoraproject.org/#alphaorder
in that it is designed to be the primary and a resumable portable medium for
computing on different computing hardware.
http://wiki.sugarlabs.org/go/Sugar_on_a_Stick/Essence

       --Fred