SparkBuild does not support cluster builds. The included emake is intended for local use only (and only has been tested for that use at this point). The next feature release of ElectricAccelerator is likely to include an emake that will allow the use of sub builds in a cluster environment, but that will only apply to the commercial version. Forward going the commercial version of emake will be a superset of the capabilities of SparkBUild, at this point that is not the case due to the timing of the releases.