From Fedora Project Wiki

xz compression change in Fedora 15
If you want to use delta ISOs for F15 or above on a system running F14 or below, see this on how to either build executables, or download prebuilt executables, to use in place of those in the native deltaiso package (which will not work on F14 or below).

Fedora delta ISOs are now hosted here.

See Delta ISOs for instructions on using delta ISOs. Some of the delta ISOs listed below have been broken into several parts using the split command. After downloading all parts, and verifying the checksums, combine them using the cat command. For example,

cat CentOS-5.4_5.5-i386-bin-DVD.diso.? > CentOS-5.4_5.5-i386-bin-DVD.diso

Experimental zsync control files may also be available here. Zsync is not currently available in the Fedora repos, but is available as a source tarball from the developer's website. RPMs and even yum repositories can also be found, for example here. Note that if this particular repo is used, then a line


should be added to network.repo, to prevent any other packages from this repo (many of which already exist in the Fedora repos) from being used.