On 04/10/2005 09:45:17 PM, seth vidal wrote:
> which is yet another readon for Fedora to adopt jigdo - the respun
iso
> could be distributed via jigdo, making very little downloading
required
> for those who had issues to be able to test the respin and see if
they
> are resolved.
>
Do me a favor.
Everytime someone mentions isos, you mention jigdo. However, what
I've
never seen you do is link to jigdo-ized releases of fedora.
try it sometime.
do a jigdo from fc4t1 to fc4t2 isos.
I wanna see what sort of bandwidth saving is possible. Rather than
just
take your word and jigdo's website word for it.
Let's get some numbers, shall we?
"Every time" is a little bit of an exageration, but yes - I confess, I
pimp jigdo - it saves me a lot of bandwidth with Debian ISO's.
With respect to a FC4T1 to FC4T2 jigdo update, there may be some
bandwidth savings, but it probably would not be much because a lot of
packages will have changed between the two respective ISO's.
Tiniest change in a package, and jigdo wants an entire new package.
Where jigdo will save bandwidth - if the test releases were released
via jigdo, I could tell it to scan my mirror of rawhide packages, and
it would only need to downloads files needed for the iso that were not
in my rawhide mirror.
With FC4T1 there were 3 major bugs on release -
1) gdm
2) firstboot
3) disk integrity check
With jigdo, it would have been possible to release a FC4T1.a that had
those fixed, since not many files on the iso's would need to be changed
to fix at least the first two issues, getting a fixed iso would be as
simple as mounting your FC4Test1 dvd iso, pointing jigdo-liste at the
FC4Test1.a jigdo file, and telling it to scan your mounted FC4Test1
dvd.
The files that were identical between the two would not need to be
redownloaded to make the new iso file, because jigdo-lite would find
them on the mounted DVD.
Where jigdo also saves bandwidth is the creation of the test releases
from people who have local rawhide mirrors. They can have jigdo-lite
scan their rawhide mirror, and it can create the iso files using mostly
packages from the local rawhide mirror - only needing to fetch those
files from the fedora server that were not present in the local rawhide
mirror.
Jigdo's biggest advantage however is that is saves on mirror disk
space, and that I believe was the original reason Debian moved to using
it.
If you have a full mirror of fedora, you have every single rpm 3 times
(one for download outside the images, one in DVD image, one in CD
image) - and noarch rpm's, you have many many times.
With jigdo, a lot of mirrors could choose not to mirror the iso images
- but instead only mirror the packages and jigdo files needed to create
CD's/DVD's - and still be able to provide CDs/DVDs to their users
without needing the disk space of all of the ISO images. I imagine this
would also greatly reduce the bandwidth needed before a release to
populate the mirrors.
The bandwidth jigdo would save going from FC4T1 to FC4T2 can be
calculated, look at the size of files that identical between the two.
Tests aren't needed, if jigdo-lite has scanned a file it needs for the
image it is creating, it uses that file - and doesn't download it.
It's probably not that great between FC4T1 and FC4T2 because a large
number of packages have been updated. Where the savings would be -
would be creating iso's for people who already have lots of current
rawhide packages (IE have jigdo-lite scan /var/cache/yum/extras-
development/ ) and the desired (but currently non-existant) respins of
test iso's to fix issues that are found within 24 hours of a release.
--
Michael A. Peters
http://mpeters.us/