Introduction to a new SIG for creation of Live DVD
Andre Robatino
andre at bwh.harvard.edu
Tue Sep 15 13:19:36 UTC 2009
On 09/14/2009 03:48 PM, Andre Robatino wrote:
> On 09/14/2009 12:05 PM, John Reiser wrote:
>>> Deltaisos are capable of saving roughly half the download size in
>>> going from Fedora N to Fedora (N+1), but only work for installation
>>> images, not live images. Is there any form of delta compression for
>>> live images which is competitive with this?
>>
>> It hasn't been productized, but approximately:
>> unsquashfs old-Live.img old-Live.tree # local ("slave")
>> unsquashfs new-Live.img new-Live.tree # remote ("master")
>> rsync remote:new-Live.tree local:old-Live.tree # "delta
>> compression" happens here
>> mksquashfs old-Live.tree new-Live.img # local
>
> Has anyone tried this on existing live images to see how much is saved
> (say going from a Fedora N to Fedora (N+1) Live CD)? I'm skeptical that
> rsync, which is completely general, would be as efficient as something
> specialized such as {make,apply}deltaiso. It may be necessary for
> someone to create a specialized tool for delta compression between live
> images, in order to be able to compress as well as deltaisos currently
> do for the install images.
I tried doing this with the Live CDs for F10 and F11. Almost the entire
content is in a single file LiveOS/squashfs.img. Attempting to use
unsquashfs on this file gives
Parallel unsquashfs: Using 1 processor
FATAL ERROR aborting: failed to read fragment table
What am I doing wrong? (I'm using the i686 live CDs. I originally
tried it on an x86_64 host, then on an i686 host after reading somewhere
that might be the problem, but it made no difference.)
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