“This chapter is from the book, ‘Cloud Computing: Concepts, Technology & Architecture‘ authored by Thomas Erl with Zaigham Mahmood and Ricardo Puttini, published by Pearson/Prentice Hall Professional, May 2013, ISBN 0133387526, Copyright 2013 Arcitura Education Inc. For more info please visit: http://www.informit.com/store/cloud-computing-concepts-technology-architecture-9780133387520“
11.1 Workload Distribution Architecture
IT resources can be horizontally scaled via the addition of one or more identical IT resources, and a load balancer that provides runtime logic capable of evenly distributing the workload among the available IT resources (Figure 11.1). The resulting workload distribution architecture reduces both IT resource over-utilization and under-utilization to an extent dependent upon the sophistication of the load balancing algorithms and runtime logic.
A redundant copy of Cloud Service A is implemented on Virtual Server B. The load balancer intercepts cloud service consumer requests and directs them to both Virtual Servers A and B to ensure even workload distribution.
This fundamental architectural model can be applied to any IT resource, with workload distribution commonly carried out in support of distributed virtual servers, cloud storage devices, and cloud services. Load balancing systems applied to specific IT resources usually produce specialized variations of this architecture that incorporate aspects of load balancing, such as:
- The service load balancing architecture explained later in this chapter
- The load balanced virtual server architecture covered in Chapter 12
- The load balanced virtual switches architecture described in Chapter 13
In addition to the base load balancer mechanism, and the virtual server and cloud storage device mechanisms to which load balancing can be applied, the following mechanisms can also be part of this cloud architecture:
- Audit Monitor – When distributing runtime workloads, the type and geographical location of the IT resources that process the data can determine whether monitoring is necessary to fulfill legal and regulatory requirements.
- Cloud Usage Monitor – Various monitors can be involved to carry out runtime workload tracking and data processing.
- Hypervisor – Workloads between hypervisors and the virtual servers that they host may require distribution.
- Logical Network Perimeter – The logical network perimeter isolates cloud consumer network boundaries in relation to how where workloads are distributed.
- Resource Cluster – Clustered IT resources in active/active mode are commonly used to support workload balancing between different cluster nodes.
- Resource Replication – This mechanism can generate new instances of virtualized IT resources in response to runtime workload distribution demands.