It is possible to run multiple instances of the Hurd in parallel, on a single instance of Mach. Other than performance ?crosstalk, they are essentially isolated. Practically, as many devices do not allow multiple non-?cooperating users, e.g., hard drive and network this is not currently possible. It can be overcome, however, by virtualizing these problematic devices.

When extra hardware is not available, it is possible to use a sub-Hurd.

Etymology

Neighborhurd is a pun on neighborhood, and a stance against hierarchies.