Database Reference
In-Depth Information
Chapter 6
Replicating Virtualized Database Servers
In general, virtualization technology is increasingly being used to improve the
manageability of software systems and lower their total cost of ownership.
Resource virtualization technologies add a flexible and programmable layer of
software between applications and the resources used by these applications. One
among several approaches for deploying data-intensive applications in cloud
platforms, called the
virtualized database servers
approach, takes advantage
of virtualization technologies by taking an existing application designed for a
conventional data center, and then porting it to run on virtual machines in the public
cloud. Such migration process usually requires minimal changes in the architecture
or the code of the deployed application. In this approach, database servers, like any
other software components, are migrated to run in virtual machines. One of the
main advantages of this approach is that the application can have full control in
dynamically allocating and configuring the physical resources of the database tier
as needed. Hence, software applications can fully utilize the elasticity feature of
the cloud environment to achieve their defined and customized scalability or cost
reduction goals. In addition, this approach enables the software applications to build
their geographically distributed database clusters. Without the cloud, building such
in-house cluster would require self-owned infrastructure which represent an option
that can be only afforded by big enterprises.
A common feature to the different cloud offerings of the NoSQL database as
a service and the relational database as a service is the creation and manage-
ment of multiple replicas of the stored data while a replication architecture is
running behind-the-scenes to enable automatic failover management and ensure
high availability of the service. In the previous chapter, experimental investigation
of customer-based observations of the consistency, data staleness and performance
properties of various cloud NoSQL databases have been carried out. In this chapter,
virtualized database servers are the main target for exploration. The aim is to set a
first yard stone in evaluating the performance characteristics of virtualized database
