Understanding Debian Sid a.k.a. Debian Unstable

Disclaimer: This text is provided mainly for educational purposes and it does contain some simplifications, so learn at your own responsibility. If any misunderstandings or harm would result because of this text techtimejourney.net and its maintainer JJ Posti will not take any responsibility from any possible scenarios that might result.

When people generally hear the word unstable they tend to think of something that is not working and remains far from functional. In Debian the term unstable does not necessarily mean the same as not functional or unsafe and below are some reasons why.

Reason 1: Debian Sid (a.k.a unstable) means literally Debian Still-in-development.

When a new Debian Stable release is made (currently Wheezy) the software has already migrated from Debian Sid repositories to Debian Testing repositories (currently Jessie) and from there to Debian Stable repositories. So, Debian has three repositories for packages which indicate how well Debian developers have tested the packages. As Debian is well known for its stability it is all but natural that Debian Stable is very very well tested. However, other Debian branches are not so bad either on stability – and they do tend to have newer versions from the programs.

Reason 2: Software maintainers try to make things better with new versions

In Unix world software develops fast. Generally, this means that when a person maintains some software and uploads a new version of it then it brings something new to the table and might also fix some previously known bugs and errors. Debian Sid gets new versions from packages very quickly as it is always still-in-development. Debian Testing usually has to wait for some time and Debian Stable does not get new major versions  until the next  of Debian Stable is out (meaning: until Debian Testing has been so well tested that it becomes the new Debian Stable).

Reason 3: Debian Sid does not have migration issues

For a desktop user Debian Stable might get troublesome as it might get a bit old on some aspects that the specific user might need. Even though Debian Testing does offer newer versions from the programs x and y it is not uncommon that some libraries that the given programs x and y  need have not still entered Debian Testing repositories because some serious bugs have been found, which have prevented the migration process. Debian Sid does not have migration issues as it gets all the packages while they are still hot and new.

Reason 4: Development does not mean that the user is at the mercy of software bugs

From the user’s perspective bugs can be troublesome if he/she does not know what problems are currently affecting packages. However, there are tools like apt-listbugs and apt-listchanges which give user all the needed data from the bugs and the changes of the packages he/she is upgrading with apt-get upgrade command before any final decisions are made. In Debian Sid I would say that apt-listbugs is highly recommended tool, so that serious problems could be avoided, while apt-listchanges is not necessarily needed if the user is not interested on the changes that the packages have undergone between the versions. In Debian Sid bugs are usually fixed very fast.

Common confusion: Debian Stable and Testing have security support but Sid does not. Debian Sid must be unsafe.

As it is true that Debian Stable and Debian Testing do have security repositories and security support this does not mean that Debian Sid is unsafe. In Sid software might get upgraded rapidly and it is of no use for Debian developers to spend a week fixing a security bug which will be fixed very quickly by the upstream package maintainer in the next  version of the package. In Debian Testing things are a bit different as the software might be “stuck” in there for a long time before it gets replaced by a new version coming from Sid: so that is why having a security support in Debian Testing is a good idea. For Debian Stable having security support is of course a must since there will be no major version upgrades available from the programs, which fix errors, until the next Stable is out: so software does need some patching and security auditing from Debian developers.

The above text contains some siplifications but tries to remain as accurate as possible. In general Debian Sid is good system to run even as it has a bit of a learning curve.  As Debian Sid is a bleeding edge version of Debian it remains good for desktop users but I would not recommend it for the ones who seek to have a super-stable and static system because then Debian Stable might be a more suitable option.