Well, I'm not going to insist on providing jigdo. However, the
situation in my mind is this one: I've downloaded Fedora 13 Beta DVD
iso previously and installed it on my system. Then, I've updated my
system regularly (using yum presto) and I use yum's "keepcache=1"
option. So, my Fedora Beta DVD iso + cached updated rpms would provide
a considerable number of files available in the next DVD iso; so if
jigdo is available I would probably be able to create the next iso
without downloading many rpm packages.
Certainly, the efficiency in this case depend on the installation. A
minimal installation will not have many rpms and so will not receive
new versions of most rpms when updating.
Thanks anyway,
Hedayat
Andre
Robatino <andre@xxxxxxxxxxxxxxx> wrote on 04/30/2010
2:14:32 PM +0450:
On 04/30/2010 04:46 AM, Hedayat Vatankhah wrote:
Hi,
It would be nice if Jigdo downloads could be also provided so that
people with previous releases (e.g. Beta release) which have downloaded
(and cached) updates could easily create new installation media without
downloading much (which will be much less than delta isos).
Jigdo/rsync/zsync all have roughly the same efficiency (ignoring the
large template file which must initially be downloaded when using jigdo)
in that they avoid downloading unchanged packages, but updated packages
must be downloaded in full. Deltaisos also avoid downloading unchanged
packages, but in addition save space for updated packages by using
deltarpms instead of full RPMs. So a deltaiso between 2 given ISOs
should always be more efficient (in terms of size) than any of the
others in doing the conversion. Of course this is assuming that a
single deltaiso between the two ISOs is available (as opposed to having
to use several to go from A to B, then from B to C, etc. which is much
less efficient). It's not feasible to produce a deltaiso between every
pair of ISOs since the number grows quadratically. However, most
testers download each TC/RC, so deltaisos just between successive
TCs/RCs are usually enough.
On the other hand, using deltarpms is expensive in terms of CPU. The
tradeoffs between downloading deltarpms vs. full RPMs are exactly the
same for using deltaisos vs. jigdo/rsync/zsync as they are for using
yum-presto vs. not using it, so anyone who currently finds yum-presto of
benefit should be better off using deltaisos vs. any of the other
choices (even if they were available).
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