This monitors the available disk space of the temporary directory, and if it gets below a certain threshold the node will be made offline.

Java tools and tests/builds often create files in the temporary directory, and may not function properly if there's no available space.

More specifically, it checks the available disk space of a partition that includes directory designated by the java.io.tmpdir system property. To check where this directory is on a given slave, go to ${rootURL}/computer/SLAVENAME/systemInfo.