enabling faster smaller downloads for yum via deltarpms

some time back, upper management at where i work, decided to migrate all our servers to SLES. i then made the decision to move my personal machines to opensuse, the opensource base of SLES, to become familiar with SUSE's administration tools and methodologies. i have since moved back to fedora but there was one feature that i loved and wished was in fedora: deltarpms

deltarpms have finally arrived as a default feature in fedora 11. it is in use in production in fedora 10 and was apparently in development phase in fedora 9.
deltarpms are basically, the delta of the previously installed rpm and the new uninstalled just release update rpm. so say you have an installed rpm like openoffice which is 50mb and there is a security update in one line of code. without deltarpms, you will be download once again the entire 50mb. however, with deltarpms, you might find the download a 100kb (yes it can be that small) deltarpm which will patch your original installed rpm with that one line of code.

well, thats the advantage: saving bandwidth when you download. but there is a disadvantage too: reconstituing the rpm requires cpu power. as a workaround, i schedule my yum updates for 3am in the morning, when no one is sitting on my pc.

the methodology of using delta updates is through a yum plugin called yum-presto. step 2 is enabling the presto repository. the commands are
  yum -y install yum-presto

next, as root edit /etc/yum.repos.d/fedora-updates.repo
under the [updates] stanza, disable the current mirrorlist by preceding the line with a hash (#) and then adding the following line:
  mirrorlist=http://presto-mirrors.anmar.eu.org/mirrorlist?repo=updates-released-f$releasever&arch=$basearch

and thats it. the next time you do a yum -y update, the presto plugin will cause yum to look at the presto repositories for updates instead and if there are any, the updates will be downloaded and your system updated via deltarpm. thereby saving you bandwidth