The Crystal Multicomputer: Design and Implementation Experience

This paper presents an overview of the hardware and software components of the Crystal multicomputer project. The goal of the Crystal project is to design and implement a vehicle that serves a variety of research projects involving distributed computation. Crystal can be used simultaneously by multiple research projects by partitioning the available processors according to the requirements of each project. Users can employ the Crystal multicomputer in several ways. Projects such as operating systems and database machines that need direct control of processor resources (clock, memory management, communication devices) can be implemented using a reliable communication service (the "nugget" that resides on each node processor. Projects that prefer a higher-level interface can be implemented using the Charlotte distributed operating system. Finally, users interested in Crystal principally as a cycle server can run UNIX® jobs on node machines using the "remote" unix service. Development, debugging, and execution of projects can take place remotely under the control of any of several UNIX hosts. Acquiring a partition of machines, resetting each machine, and then loading an application onto each machine is performed by invoking a UNIX-resident program (the "nuggetmaster"). Communication with node machines in a partition is facilitated by a virtual terminal and window mechanism. Crystal is fully operational and has been used to support a variety of research projects. To illustrate the flexibility provided by the Crystal environment, four of these projects are described.