Operating System Concepts, Seventh Edition

Chapter 17. Distributed File Systems

In the previous chapter, we discussed network construction and the low-level protocols needed for messages to be transferred between systems. Now we examine one use of this infrastructure. A distributed file system (DFS) is a distributed implementation of the classical time-sharing model of a file system, where multiple users share files and storage resources (Chapter 11). The purpose of a DFS is to support the same kind of sharing when the files are physically dispersed among the sites of a distributed system.

In this chapter, we describe how a DFS can be designed and implemented. First, we discuss common concepts on which DFSs are based. Then, we illustrate our concepts by examining one influential DFS—the Andrew file system (AFS).

CHAPTER OBJECTIVES

• To explain the naming mechanism that provides location transparency and independence.

• To describe the various methods for accessing distributed files.

• To contrast stateful and stateless distributed file servers.

• To show how replication of files on different machines in a is a useful redundancy for improving availability. file replication

• To introduce the Andrew file system (AFS) as an example of a distributed file system.

Background

As we noted in the preceding chapter, a distributed system is a collection of loosely coupled computers interconnected by a communication network. These computers can share physically dispersed files by using a distributed file system (DFS). In this chapter, we use the term ...