Comment 5 for bug 301289

I prepared a ZSYNC file to test download of Ubuntu 8.04.2 images.

ubuntu-8.04.2-server-i386.iso.zsync was created in this way:

FILE="ubuntu-8.04.2-server-i386.iso"; zsyncmake -v -u "$FILE" -u "http://releases.ubuntu.com/8.04.2/$FILE" -f "$FILE" -o "$FILE.zsync" "$FILE"

To test zsync update, copy old ISO image to some temporary directory at your disk. I use ubuntu-8.04.1-server-i386.iso in my example to build ubuntu-8.04.2-server-i386.iso. Download ubuntu-8.04.2-server-i386.iso.zsync to the same directory and run this command:

zsync -i ./ubuntu-8.04.1-server-i386.iso ./ubuntu-8.04.2-server-i386.iso.zsync

With support from zsync, you have to download only 50% of the ISO file.

In the case you don't have old ISO image,you can try to download while ISO image with this command:

zsync ./ubuntu-8.04.2-server-i386.iso.zsync

In this case, zsync doesn't add real value compared with wget and other similar tools.

In the case that official Ubuntu server will support ZSYNC, you can use this (only sci-fi now):

zsync -i ./ubuntu-8.04.1-server-i386.iso http://releases.ubuntu.com/8.04.2/ubuntu-8.04.2-server-i386.iso.zsync

And you can use "-u" option to overwrite URL embedded in the zsync file with server you prefer:

zsync -i ./ubuntu-8.04.1-server-i386.iso -u http://ftp.sh.cvut.cz/MIRRORS/ubuntu-releases/releases/releases/8.04.2/ubuntu-8.04.2-server-i386.iso ./ubuntu-8.04.2-server-i386.iso.zsync