# PLUM Introduction

PLUM is a tool for estimating facility resource requirements through a Monte-Carlo algorithm. It is used for strategic planning. The general idea is that we enter all the rack data, all the constraints about which racks require other racks to operate, and all the station capabilities. Then we make a "run" and get as output a graph showing what percentage of random facility sets were able to run. The run consists of PLUM generating a selection of facility combinations that fit the constraints, and totaling what resources they need. A set of PostScript graphs is then generated, plotting what percentage of combinations exceeded each resource versus the number of facilities in the combination.

PLUM has three main parts: the interface, which you'll use to make runs and enter data; the database, which is where all the rack data and raw run output is stored; and the modeler tools, which are used to actually generate the run outputs. The database and modeler tools are managed automatically by the interface; you will only ever need to know how to use it.

PLUM graphs are only really uesful for strategic planning. The numbers are based on a random selection of racks, and the requirements of each rack are only as valid as what the payload developers request. If you are intending to use this tool to make exact, short-term decisions, then you are using the wrong tool. If you are trying to make a long-term planning decision on what resource to invest more heavily in, then you're in the right place.