Rex: A toolset for reproducing software experiments

Software experiments such as BLAST are hard to reproduce even if identical hardware is available because external data sets could have changed, software used in the original experiment may be unavailable, or the input parameters for the experiment may not be documented. This paper presents Rex, a toolset that allows one to record an experiment and archive its apparatus, replay an experiment, conduct new experiments on a recorded apparatus, and compare differences between experiments. The execution time overhead of recording experiments is on average about 2%; the space overhead of an archive ranges from 8 MB to 5 GB.