I have 3 servers of exactly the same configuration. Is it possible to install linux on 1 exactly the way I want it, then clone over the installation? What would be the problems with doing this?
What these allow you to do is define a system state on a master node, and then propogate this state onto other box's. For example you can define that each node should have package X, Y and Z, with a certain directory structure and specific files/users/configuration. Then the master will continually enforce this state onto all of its nodes. This requires some time to setup and configure properly but it can work wonders. There is a tool called Blueprint that will allow you to map out a running system and export it into a puppet recipe (or its own internal thing).
You could also just clone the HD's into another HD using Norton Ghost or Clonezilla but as MadHatter mentioned you might run into issues.
The usual big problems arise when details of the source system's hardware have been embedded in config files. These include network interface config files (which often have MAC addresses embedded in them), md RAID config files (which often have the UUIDs of physical devices in them) and
modprobe.conf and similar files (that often have links between hardware-specific kernel modules and the various NICs, HDD controllers, etc. that they refer to).
There can also be issues with licence keys for proprietary software, which are often designed to be tied to hardware. But you weren't running any nasty proprietary software, were you? (grin)