Well its that time again, the Ubuntu community is just about ready to launch another fantastic release and with that release the worlds interweb tubes are going to get clogged as everyone upgrades. It’s about this time that I always start thinking about ways to be more efficient with my bandwidth.
Bittorrent, of course, is a great improvement over the traditional direct download method but in some cases there are potentially more efficient methods to use. I’d like to outline (as I do with every release) how to update your current ubuntu images using Jigdo.
Jigdo, if you’re not familiar, takes a current Ubuntu image and compares its contained packages with the packages within an updated image (ie; alpha vs beta, beta vs RC, RC vs final). Using this method you’re only downloading the packages that have *changed* between images and not the entire image again. The morning RC was released I used jigdo against my local ubuntu package mirror and had the new image in about a minute!
Installing Jigdo
Jigdo is available within the Ubuntu repositories. To install Jigdo you can run the command:
sudo aptitude install jigdo-file
Using Jigdo
Jigdo requires a .jigdo file, which outlines what the latest image *should* have, which is then compared to the previous image file that you already have on the machine. The previous image can be burned and in the drive or loop-mounted (mount -o loop file.iso /mnt). So, to begin you’ll need to start Jigdo and give it the path to a .jigdo file:
jigdo-lite http://us.releases.ubuntu.com/hardy/ubuntu-8.04-rc-alternate-i386.jigdo
The .jigdo file can be found on most download sites, look for it just below the .iso or .torrent files.
Jigdo will then download that .jigdo file and read the contents of what package versions should be in the latest release. It will then ask you for the image you want to compare it to, which you can point it to your loaded disk or mounted .iso.
If not much has changed between the images (its *really* efficient for updating dailies!) it should be finished pretty quickly. The more changes there are the more packages it’ll have to download. When it has being able to find, or has downloaded the required updated packages, it’ll create a new .iso image for you. Tada! You have an upgraded image and you’ve used much less bandwidth than traditional methods.
note: using Jigdo to compare a 7.10 image vs an 8.04 image is not going to offer any improvements–everything has been changed. It is best used for incremental updates, like beta to RC, RC to final, etc.
For more information on using Jigdo for updating Ubuntu images see the JigdoDownloadHowTo Wiki page.
I decided to try and join the domain during the install. 
