FAI is an automated installation tool to install or deploy Debian GNU/Linux and other distributions on a bunch of different hosts or a Cluster. It’s more flexible than other tools like kickstart for Red Hat, autoyast and alice for SuSE or Jumpstart for SUN Solaris. FAI can also be used for configuration management of a running system.
FAI is a scalable method for installing and updating all your computers unattended with little effort involved. It’s a centralized management system for your Linux deployment.
FAI’s target group are system administrators who have to install Linux onto one or even hundreds of computers. It’s not only a tool for doing a Cluster installation but a general purpose installation tool. It can be used for installing a Beowulf cluster, a rendering farm, a web server farm, or a linux laboratory or a classroom. Even installing a HPC cluster or a GRID and fabric management can be realized by FAI. Large-scale linux networks with different hardware and different installation requirements are easy to establish using FAI and its class concept. Remote OS installations, Linux rollout, mass unattended installation and automated server provisioning are other topics for FAI. The city of Munich is using the combination of GOsa and FAI for their Limux project.
— quoting FAI’s homepage
Whereas preseeding d-i (Debian-Installer) is one approach of installing Debian systems the advantage of FAI is that you aren’t limited to Debian systems, you’re more flexible in regards to configuration and you can also manage your systems after installing them as well – for example using softupdates for system updates. Find official documentation at the FAI homepage and in the FAI-wiki.
Tip: If you’re still using setup-harddisks make sure to check out the new setup-storage mechanism of recent FAI versions (for automatically preparing storage devices) which supports installation on LVM and SW-RAID devices.