Fedora Might End Up Disabling Delta RPMs By Default

Going back to 2009 with Fedora 11 has been delta RPM support to enable support with Yum for these packages that just contain the differences between one installed RPM version to the next version. With Fedora frequently pushing down new packages, delta RPMs have allowed those in bandwidth-constrained environments to more easily download updates since the file sizes of the deltas tend to be significantly smaller than full RPMs. Additionally, it's placed less of a burden on the Fedora infrastructure by having less disk space and bandwidth requirements. However, with DNF it looks like Fedora could revert to going back to full RPMs for distribution of updates.

Right now the DNF package manager that's expected to replace Yum in Fedora 22 doesn't enable delta RPM support by default. The developers' reasoning for disabling delta RPMs by default is that it's not an always faster process -- if you have a very fast Internet connection, it's easier to download full RPMs rather than spending the CPU time and resources to reconstruct the delta RPMs back into a usable package for installation. Their approach is to hold off on enabling delta RPMs by default until Fedora 22 is out with DNF by default to see what users request. With delta RPMs you don't need a copy of the original RPM sitting around but it does work too for installed RPMs onto the system, but again, it takes some time to update.

There's Fedora users polarized on the matter of whether delta RPMs are good enough: some care about bandwidth and capped Internet connections that want the feature by default while others think it's a poor feature and encourage DNF's proposed change. Fedora stakeholders with their views have been chiming in via this bug report about a request for enhancement to enable delta RPMs by default for DNF. The discussion has also poured over onto the Fedora devel list.

Red Hat / Fedora has moved a long way in package management compared to ten years ago...

Fedora Project Leader Matthew Miller most recently chimed in that when DNF is to be the default package manager, changing of the default settings would need to go through the FESCo-approved process for Fedora feature changes. How do you feel though about delta packages by default? Let us know in the forums or chime in on the bug report or mailing list thread.