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Consolidation in the Data Center

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Data center consolidation is about reducing the number of devices you have to manage and reducing the number of ways you use to manage them. This article introduces various types of consolidations you can perform - servers, applications, storage, shared services, networks, and people resources - and describes some of the benefits of each type of consolidation.
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When we started working on consolidation four years ago, the focus was on server consolidation; now, the emphasis has changed. When you walk into a data center and look around, everything you see is a candidate for consolidation. Today, consolidation is about reducing the number of devices you have to manage and reducing the number of ways you use to manage them.

With that in mind, this Sun BluePrints™ OnLine article takes a look at some of the consolidation opportunities that exist in today's Information Technology (IT) environment. These include:

  • "Consolidating Servers,"

  • "Consolidating Applications,"

  • "Consolidating Storage,"

  • "Consolidating Shared Services,"

  • "Consolidating Networks,"

  • "Consolidating Data Centers,"

  • "Consolidating People Resources and Processes,"

Consolidating Servers

Servers are still the primary focal point for consolidation because they are so obvious. Whether you have 100 servers or 5000 servers, you probably have too many to manage effectively. Today's distributed computing environment lends itself to a proliferation of servers. Reducing and controlling the number of devices to manage and simplifying ways to manage them is the goal of most IT groups.

Applying Vertical and Horizontal Scalability

When we talk about consolidating servers, we generally refer to scaling them vertically or horizontally.

  • Vertical scalability enables you to reduce the number of servers by consolidating multiple applications onto a single server.

  • Horizontal scalability enables you to deal with increased workloads through the replication of servers and the distribution of workloads across those servers.

By thinking of consolidation in these terms, you begin to define the approach required by your particular consolidation project. Once you decide whether your consolidation project requires horizontal scaling, vertical scaling, or a combination of the two, you can further refine your approach by identifying patterns in your server population. Examples of vertical and horizontal scaling are presented in the Sun BluePrints book Consolidation in the Data Center (ISBN #0-13-045495-8).

Identifying Patterns in an End-to-End Architecture

In the end-to-end architectures that are prevalent today, tiers of servers are specialized for particular tasks. When you look at consolidating servers, you need to look for patterns in your server population. When you identify these patterns within tiers, you can start to devise a consolidation strategy. Scalability is the key, here. Because you are expected to deliver predictable service levels in response to unpredictable workloads, it is important that you use the right type of scalability for each part of a consolidated architecture. The following sections describe common patterns in an end-to-end architecture.

For consolidation discussions, we generally assume that there are three server types, or tiers:

  • The presentation tier is the closest tier to the end user.

  • The business, or middleware, tier is where applications or middleware run in conjunction with the other tiers.

  • The resource tier is where large, scalable servers run mission-critical applications and databases.

Although architectures with these characteristics have been around for awhile, most corporations still have many servers running monolithic applications. In many cases, these are older servers running mature applications. These servers are generally excellent candidates for server and application consolidation.

Figure 5FIGURE 0-1 End-to-End Architecture

Presentation Tier

As you get closer to the Internet and the delivery devices for your applications, the most common techniques for scalability are replication and load balancing across an array of generally small servers. This is usually referred to as horizontal scalability.

On the presentation tier, you usually find several small, one or two processor servers running UNIX™, Linux, or Microsoft Windows. Because current architectures call for many small servers in this tier, the opportunities for consolidating to fewer servers are limited. Despite these limitations, there is still ample opportunity to implement standards and best practices to simplify the management of these servers and to reduce total cost of ownership (TCO).

Business Tier

After the presentation tier, you find business tier servers. These generally run applications or middleware in conjunction with the other tiers. While we used to see primarily horizontal scaling in this tier, there is growing interest in reducing the number of applications using vertical scalability, as well.

Resource Tier

The resource tier is usually thought of as the heart of the data center. It is characterized by large, scalable servers that run mission-critical applications and databases. We usually find the most interest in vertical scalability and server consolidation on this tier.

Identifying Types of Consolidation

Some major consulting groups identify different categories of server consolidation. For example, Gartner refers to physical, logical, and rational consolidation groups—categories we define in the following sections. The techniques used to achieve these specific types of consolidations are discussed in later chapters.

Physical Consolidation

Physical consolidation involves consolidating data centers and moving servers to fewer physical locations. The theory behind physical consolidation is that by having servers in fewer physical locations, you can achieve management consistencies and economies of scale more easily than you can when your servers are dispersed. Physical consolidations may also enable you to reduce data center real estate costs. It is generally felt that physical consolidation has the lowest risk, but that it also has the lowest payback.

Logical Consolidation

Logical consolidation involves implementing standards and best practices across your server population. By doing this, you can realize substantial benefits in the productivity of your IT staff. They can manage the environment more efficiently and more effectively. This can often result in lower systems management costs and in lower TCO. Logical consolidation is often implemented with physical consolidation and rationalization.


Rationalization involves the deployment of multiple applications on fewer, larger servers and in fewer instances of the operating system (OS). Because TCO reduction is closely tied to the number of instances of an OS you manage, reducing the number is the best way to reduce TCO. While rationalization is the riskiest form of server consolidation, it offers the biggest TCO reduction and return on investment (ROI).

Because of its potential to reduce TCO and increase ROI, we find that most of our customers find rationalization to be the most attractive method for consolidation, despite its higher risks. During a recent web seminar on consolidation, we polled over 300 attendees on whether their main interest was in physical consolidation, logical consolidation, or rationalization. Over 85 percent said their primary interest was in rationalization.

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