Can we have a Delta-DVD release

[James Gallagher]

--- On Tue, 21/4/09, Andre Robatino <andre at bwh.harvard.edu> wrote:

> From: Andre Robatino <andre at bwh.harvard.edu>
> Subject: Re: Can we have a Delta-DVD release
> To: fedora-devel-list at redhat.com
> Date: Tuesday, 21 April, 2009, 9:05 PM
> > So there is! Doesn't work on F9
> -> F10 but on F10 -> F11 beta DVD (x86_64)
> > I get a delta iso image of 2.2GB, about 53% less than
> the full iso.
> > Hmm, not as good as I was expecting, probably not
> worth making a fuss > about unless we could get <1GB.
> 
> A lot of people would probably be very happy with cutting
> the download in half.  On a 768 Kbit/s connection it
> would reduce download time from about 12 hours to six. 
> If the tool doesn't take too long to do the reconstruction
> after downloading, and if it's reliable (so one doesn't have
> to download 2GB only to find out it doesn't work, then
> download the full 4GB anyway) the deltaiso should be
> available as a download option.
> 
> -----Inline Attachment Follows-----
> 
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The bad news is the reconstruction is quite slow, ~40 mins on a 2GHz Core 2 Duo, 2GB ram. Here are the full stats, for the delta between F10 final and F11 beta DVD x86_64:

ls -lh Fedora-11-Beta-x86_64-DVD.iso 
-rw-rw-r-- 1 user user 4.1G 2009-04-21 17:25 Fedora-11-Beta-x86_64-DVD.iso


makedelta iso Fedora-10-x86_64-DVD.iso Fedora-11-Beta-x86_64-DVD.iso F10_F11_delta.iso

ls -lh F10_F11_delta.iso
-rw-rw-r-- 1 user user 2.2G 2009-04-21 19:33 F10_F11_delta.iso

(53% of the size of the full F11 dvd)


time applydeltaiso Fedora-10-x86_64-DVD.iso F10_F11_delta.iso F11_reconstructed.iso
...
iso sucessfully re-created, md5sum: 9dc917523132a3d269c59c91b647525a

real	41m8.534s
user	37m53.129s
sys	0m34.155s


ls -lh F11_reconstructed.iso 
-rw-rw-r-- 1 user user 4.1G 2009-04-21 22:45 F11_reconstructed.iso


md5sum Fedora-11-Beta-x86_64-DVD.iso
9dc917523132a3d269c59c91b647525a


So, the delta iso image is ~half the size of the full iso, and it takes ~40 mins to reconstruct the full iso (on a 2GHz core2 Duo, 2GB Ram).

Now a question for anyone: does the F11 beta release contain lots of debug code and if so would you expect the final dvd to have a smaller delta iso?

And one further point: wouldn't this be particularly useful for successive test releases, alphas, beta, release-candidates, since the deltas would be tiny.