Server Consolidation: Benefits and Challenges

Archived Published: 28 March 2002 ID: G00105486


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Server consolidation promises large benefits but is ill-defined and immature. Enterprises should take a step-by-step approach to obtain the benefits provided by the different types of consolidation.

Table of Contents



There has been a strong trend toward more server consolidation since 1997, led by enterprises in the United States, Canada and Western Europe. A 1998 Gartner client survey among those responsible for server deployment found that 30 percent were already consolidating, 45 percent were considering or evaluating a form of consolidation, and 25 percent had no intention of consolidating. At the December 2001 Gartner Data Center Conference, a similar survey found that these proportions had changed to 69 percent, 25 percent and 6 percent respectively (see Figure 1), indicating the growing desire to consolidate servers in the enterprise data center.

Figure 1. The Trend to Server Consolidation
Research image courtesy of Gartner, Inc.

Source: Gartner Research

Mainframe server and workload consolidation is well-understood and has been commonplace for the past 20 years. However, the focus is now on distributed platforms and, in particular, on server consolidation for the major Unix variants and for Windows platforms. The drive to consolidate Unix platforms actually began in 1997/98 and the main rationalization tool was the Sun Enterprise 10000 with dynamic domains. The demand for Windows consolidation began to increase in late 2000 and early 2001.

The magnitude of the server-management problem can be seen in any typical enterprise data center, which likely contains hundreds of Unix and Intel servers. Adding a single application typically adds three to five servers to the data center for such things as production, development, testing, and backup. Many of the distributed servers run at very low utilizations. No wonder, then, that enterprises are seeking to consolidate their servers. Storage consolidation is also a growing concern, but not necessarily tied to server consolidation.

Different Types of Server Consolidation

Server consolidation can mean different things. There is a lack of standard definitions and confusion over the various ways that consolidation can be addressed. Defining consolidation is complex, given the broad range of projects that are labeled in this way. Gartner divides consolidation projects into three types:

  • Logical consolidation, where there is no physical relocation of servers and the goal is to implement common processes and enable standard systems management procedures across the server applications.

  • Physical consolidation, which entails the colocation of multiple platforms at fewer locations.

  • Rationalized consolidation, which means implementing multiple applications on fewer, more-powerful platforms, usually through partitioning and workload management.

One of the first types of rationalized consolidation that enterprises are looking to accomplish is to consolidate similar workloads such as Web serving, file servers, print servers, e-mail servers and database applications. Although using workload management for consolidation of different database managers (Oracle and Sybase, for example) is still very difficult, or near impossible, the consolidation of applications with the same database manager is now technically feasible.

Consolidation Provides a Range of Benefits

Most enterprises see the benefits of server consolidation in terms of better management of systems and lower costs. However, consolidation can provide other benefits, such as better security and higher service levels. In some cases, though, server consolidation may increase bandwidth costs and decrease network performance beyond acceptable levels. It is important to understand that each type of consolidation offers different levels and types of potential cost savings and that the savings will vary according to the technical environment and degree of consolidation accomplished. A very important area to investigate and understand is the impact of consolidation on software license costs. Depending on the vendor's pricing structure, it is possible that software costs may actually increase when moving to a larger server.

Storage consolidation, based on enterprise storage, storage-area networks (SANs) or network-attached storage (NAS), can provide capacity-management economies of scale, better backup techniques and the connectivity to support some forms of data sharing. During the past few years, major enterprise disk vendors and leading midrange storage vendors have developed hardware suitable for storage consolidation, and software for effective management of consolidated storage.

Achieving the Benefits and Understanding the Challenges

Logical, physical and rationalized consolidation can provide progressively greater net operational savings, greater return on investment and greater end-user service benefits. However, they also involve progressively greater risks. Pursuing the ultimate consolidation goal of a single system image for all distributed server applications can yield large rewards when balanced with the expense, but the potential for a poor or failed implementation is far greater. We recommend taking a step-by-step approach and investigating each type of consolidation to evaluate potential net savings.

Server consolidation is not a simple task, and many hurdles have to be overcome to ensure success. Unfortunately, it's not possible to buy off-the-shelf server consolidation solutions (despite the claims made in vendor marketing brochures). Although many Unix and Intel system vendors such as IBM, Sun Microsystems, Hewlett-Packard, Compaq Computer, Unisys and Microsoft have major projects under way to provide server consolidation technologies (e.g., partitioning and enhanced workload management), much more needs to be done.

This Hardware Platforms Spotlight describes the different types of consolidation, the potential benefits and pitfalls of consolidation, and some capabilities that already exist for consolidation. We have assembled research from Gartner's leading analysts in the areas of storage, servers, database and software asset management. This research covers issues raised by Gartner clients, and areas that Gartner believes are critical to understanding the confusing world of server and workload consolidation. By following the advice given in this Spotlight, enterprises will understand the realities of server consolidation and will be able to make sensible decisions that ensure they achieve meaningful benefits.

A future Spotlight will examine the current "state of the art" in the technologies being offered by various vendors to aid the consolidation effort.


"Recognizing the Three Types of Server Consolidation" ( COM-15-6462 ). Identifies the different types of server and workload consolidation and provides some common definitions to help bring structure to the "alphabet soup" of vendor claims. By John Phelps

"Choosing Data Center Locations for Consolidated Servers" ( DF-15-6952 ). Looks at the physical aspects of consolidation, particularly data center site selection, usually driven by a desire to merge data centers into fewer locations. By Carl Claunch and Josh Krischer

"Creating a Server Consolidation Project Plan" ( COM-15-6954 ). Provides a checklist that will ease the planning process and minimize the risks. By Carl Claunch and Josh Krischer

"Leading a Server Consolidation Effort" ( COM-15-9196 ). Provides a checklist of the most important elements for the project leader to consider. By Carl Claunch and John Phelps

“Using SAN and NAS Technologies to Consolidate Storage" ( COM-15-6973 ). Explains how NAS and SAN environments can be used for storage consolidation independently of a server consolidation project. By Stanley Zaffos

"Consolidating Servers Cuts TCO Significantly — Sometimes" ( DF-15-6463 ). Explores the areas where consolidation can reduce the IS organization's TCO, and where it might not. By John Phelps

"Gaining the Non-TCO Benefits of Server Consolidation" ( DF-15-7113 ). Examines the other, non-TCO, benefits and downsides of consolidation. By Carl Claunch and John Phelps

"Software Licensing Implications of Server Consolidation" ( DF-15-7404 ). Exposes the issues and the effects of changing software licensing models, which are poorly understood but crucial to the overall success of server consolidation. By Frank DeSalvo

"Understanding Three Styles of Database Consolidation" ( COM-15-6784 ). Looks at the current capability to consolidate multiple database applications on the same server. By Jon Rubin

"Data Mart Consolidation: Strengthening Trend of 2002" ( SPA-15-7450 ). Examines the trend toward deploying a data warehouse instead of several data marts, an increasingly attractive option for enterprises under pressure to reduce costs and complexities. By Kevin Strange

"Guidelines for Data Consolidation" ( DF-15-7260 ). Provides guidelines for optimizing the balance between centralized and decentralized data topologies. By Kevin Strange

"Server Consolidation Roadblocks Exposed" ( DF-15-7060 ). Looks at the pitfalls of server consolidation that must be considered to ensure a successful consolidation project. By John Phelps and Carl Claunch

© 2002 Gartner, Inc. and/or its Affiliates. All Rights Reserved. Reproduction and distribution of this publication in any form without prior written permission is forbidden. The information contained herein has been obtained from sources believed to be reliable. Gartner disclaims all warranties as to the accuracy, completeness or adequacy of such information. Although Gartners research may discuss legal issues related to the information technology business, Gartner does not provide legal advice or services and its research should not be construed or used as such. Gartner shall have no liability for errors, omissions or inadequacies in the information contained herein or for interpretations thereof. The opinions expressed herein are subject to change without notice.

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