Wednesday, January 21, 2009

Sould I Enable Ubuntu Backports ?

Yes, but through pinning.

The problem with just enabling the backports repository (without pinning) arise when you upgrade you system. You will get a lot of updates, from the backports repository, that you don't want. With pinning enabled, when you do a normal upgrade you will only get the updated pacakges from the updates repository. If you want some packages from the backports repository you have to say it explicitely.

Pinning allows you to keep your system as close to the normal repositories as possible, and only use the backports repositories when you have to. This is achieved by assigning a lower than the default priority to the backports repositories. When you want a package from the backports repositories you just elevate the backports repositories priority.

It's possible to upgrade just the package you want and even choose the version. You can learn everything about the pinning method in my previous post How To Enable Ubuntu / Kubuntu Backports Through Pinning.


The fact is that there are some concerns about backports stability. I will just quote Canonical (emphasis mine):

"Backports candidates are tested by several Backports developers and community contributors before they are allowed to be placed in the repository. Backports packages are thus safer to use than the development distribution. At minimum the packages should be usable in a manner that the average Backports developer could test. However, given the nature of introducing newer versioned packages from a development distribution into a stable, released distribution, problems can arise. The most common side-effects would be a bug that escaped testing, or a new configuration file format (or other kind of incompatibility). If you have problems with a Backports package please report it in the Backports bugtracker and not the main Ubuntu one.
Due to the nature and purpose of Backports, it is not as "stable" as the previously mentioned update repositories, for a variety of reasons.
  • Backports are designed to provide new features. These new features may be unfamiliar to users and require a period of re-learning to become familiar with their favorite application again.
  • Backports may introduce differing configuration file options or behavior that may catch an administrator off guard. For this reason it's not encouraged to upgrade backports as a part of an automated procedure on high-stability production environments.
  • Backports are newer software by definition, and newer software tends to be tested by fewer people. The risk for an uncaught bug is increased.

In assessing the "stability" of backports, it's important to define the term stability first. In terms of "the behavior I see today is the same as the behavior I'll see after applying a bunch of backports updates", Backports is fairly unstable. New apps introduced via backports may have significantly changed behavior or interfaces. In terms of "applying a backport will completely break my system", Backports is fairly stable. A great deal of work goes into testing backports and it's highly unlikely for a backport to be a severe regression from the version it replaces.

The user should judge for himself if Backports are appropriate for his purposes."

References:
Ubuntu Backports

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