INTRODUCTION

The word replicate means “to produce a copy of itself” and originates from the Latin word replicates. The word synchronize is defined by the Webster dictionary to mean “to represent or arrange (events) to indicate coincidence or coexistence.” Synchronization and replication are two essential operations in distributed computing. Although synchronization can mean a variety of things, replication is typically used in reference to data. Like the literal definitions of synchronization and replication in the English language, their definitions within the field of computing are different but related. In this chapter, we will limit our discussion of synchronization and replication to data synchronization and data replication. As you may have already noted, we used the term synchronization, in Chapter 8, when synchronizing contents and actions transmitted across multiple communication channels. We are discussing synchronization in the context of data replication in this chapter.

Data replication, in its broadest sense, simply refers to copying data from one or more data storage locations to one or more other data storage locations. Note that these locations are virtual locations and not physical locations—it is not required for the virtual locations to be at different physical locations. The taxonomy of the types of replication technologies depends on the domain problem as well as the infrastructure on which replication is being performed. However, we can break nearly all data replication into two groups: complete replication and partial replication.