Plan 9 from Bell Labs

Glenda, The Plan 9 Mascot

Introduction

Plan 9 from Bell Labs (here on referred to simply as Plan 9) is a Distributed Operating system created by the Computing Science Research Center of AT&T Bell Laboratories, Which was also the group that developed Unix, and the C programming language[3]. It was first released in 1993 to various universities, and given a full release to the general public in 1995[3]. The most unique and interesting aspect of Plan 9 is that it represents all system interfaces via the filesystem including things not normally treated as files, like networking and the user interface.[3] That is to say, everything can be treated like a file, and thus can have read and write operations preformed on it. You would for instance, write Data to the network as though it were a file, and another computer would read that data. It was designed to be used in a distributed capacity, with some central computers for computation, a File server and many terminals for access, all of which is treated as one large system.

This report will go through the various aspects of the Plan 9 operating system and it's Distributed Operating system properties. Plan 9 was envisioned with 3 primary goals in mind, and this report will go into detail on each. First, All resources of the system should be represented as files in the filesystem[3]. Second, Given Application view should see an entire system as belonging to a single coherent namespace.[3] This should be independent of whether or not a given resource is local or remotely accessed. Two given namespaces might not show the same data, but all the data a given application or system sees should be presented as one namespace. Finally, all communication should be done via a standard communication protocol, which is called 9P. This report will also go over how a standard plan9 network would be set up, and my failed attempts to set up a plan9 network myself.

A Standard Plan 9 System

Before we go into the details of a Plan 9 system, lets go over how a standard Plan 9 system would be implemented. A standard Plan 9 system is composed of 3 major parts; File servers for storage, CPU servers for computation, and Terminals for access.[7] File Servers and CPU Servers are normally centralized machines with multiprocessing capacities and many concurrent network connections. They require many fast network connections between each other, for maximized computation efficiency and request handling.

Terminals are can be either local or remote, and connected to the primary cluster via something as simple as an ethernet cable or something more complex such as a connection over the internet.[7] Terminal users can choose how they wish to distribute their workload; a local user could do most basic computation him or herself and only use the CPU servers for more complex tasks as they would be able to quickly access files on the Fileserver. A remote user could choose to do most basic computations on the CPU server, as it would be able to quickly access the Fileservers sending only the completed task to the remote terminal. This can be done because Both Terminals and CPU servers run on the same Kernel, making it easy for a Terminal user to assign a task to either his own terminal or a remote Server.[7]