From Fedora Project Wiki

Different install disc sets (currently either the 1-disc DVD set, or the several-disc CD set) for the same arch contain the same set of RPMs. Since the rsync algorithm can detect matching blocks between local and remote files (even at different offsets, unlike BitTorrent), this makes it possible to efficiently convert between different install disc sets with very little transfer of data (no more than a few percent of the full size). The content of the netinst disc is almost identical to data contained in the first disc in each install disc set, so generating the netinst disc from the first install disc in any of the sets can be done efficiently as well. In the following examples, the rsync URL was obtained by picking a Fedora mirror with an rsync server, getting the http:// or ftp:// URL for the specific ISO, then replacing either http:// or ftp:// with rsync://.

Converting Between Install Disc Sets

Suppose one has install disc set A, and wants to generate install disc set B. For each disc in set B, perform the following steps:

  • Use the cat command to combine all the discs in set A into a single file with the same name as the set B disc.
  • Run rsync on this file to convert it into the actual set B disc.

For example, suppose one has the 5-disc Fedora 13 i386 CD set, and wants to generate the 1-disc Fedora 13 i386 DVD set. Then:

  • cat Fedora-13-i386-disc?.iso > Fedora-13-i386-DVD.iso
  • rsync -avzP rsync:// Fedora-13-i386-DVD.iso

If one has the 1-disc Fedora 13 i386 DVD set, and wants to generate the 5-disc Fedora 13 i386 CD set, then do the following two steps for disc 1, and repeat for discs 2 through 5:

  • cat Fedora-13-i386-DVD.iso > Fedora-13-i386-disc1.iso
    (Since the DVD set has only one disc, this is the same as using cp to make a copy.)
  • rsync -avzP rsync:// Fedora-13-i386-disc1.iso

Generating the Netinst Disc

Make a copy of the first disc in the install disc set, giving it the same name as the netinst disc, for example:

cp  Fedora-13-i386-disc1.iso Fedora-13-i386-netinst.iso

Run rsync on this file to convert it into the actual netinst disc:

rsync -avzP rsync:// Fedora-13-i386-netinst.iso