I recently tried out a test system with an Ubuntu Server 7.10 JeOS build. The JeOS (Just Enough Operating System, pronounced “juice” ) concept for Linux works well if one needs just enough to run a test system. JeOS builds are popular for software vendors that are making purpose built systems, small footprint test systems, or a virtual appliance environment for popular virtualization technologies.
What composes a JeOS distro?
Simply put, not much. JeOS distributions are a skinny, bare-bones build made to occupy a small footprint and provide only explicit system services on the install. The JeOS distributions follow their full build counterparts in the same versioning and install interface, just with less options for install from the CD media.
Start with nothing, add only what is needed
JeOS distributions are perfect for this practice for many reasons. My particular need was an external facing DNS server, so the skinny JeOS did a great job and installed the DNS server, a boot loader and the OS essentials. This also made for a smaller drive footprint - only 500 MB (as a virtual system). The JeOS install CDs are smaller than the full version counterparts, but have a similar look and feel for the install process.
Should you need to add a package that was not on the CD, you can use the standard retrieval tools. For my Ubuntu 7.10 JeOS system, this included
sudo apt-get. This option is handy should I need to add a web server engine or database. Also, you can make the JeOS builds fit your existing enterprise Linux environments by adding the tools and packages you expect to be installed, but starting with less on the base install.
JeOS distributions do not run a different Linux kernel than the full version equivalent, they simply have less packages. Ubuntu 7.10 Gutsy Gibbon and the JeOS equivalent are both at kernel 2.6.22. Plus, Canonical Ltd. provides support options for the Ubuntu JeOS – which is nice.