SAN Buyers Guide: Part I

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Today, many enterprises that are currently working in a direct attached storage (DAS) environment, are investigating advanced storage options and implementation plans to move to the centrally pooled storage arena by creating and deploying their first storage area network (SAN). Storage area network (SAN) technology provides a variety of business and technical advantages over DAS and other data storage architectures (networked attached storage (NAS), etc.). Most enterprises who are considering a move to their first SAN, recognize the technical or business value, but they often need further justification for determining their needs, preserving the required infrastructure investment and coverage of hidden costs (such as software, warranties, etc.). With that in mind, this article is a general buyers guide for determining the minimum amount of resources and equipment needed to create your first SAN in order to achieve a financial payback (return on investment (ROI)); and, justification for moving from your current DAS environment
to a SAN system.

Business Case Analysis

A solid business case analysis should be performed in the planning phases of SAN design and justification. The reason for this is that a SAN can radically impact the operational enterprise infrastructure. Also, the cost of a SAN infrastructure itself (without considering the cost of storage arrays) is often very high. In other words, without proper planning and impact analysis, the very high cost of Fibre Channel (FC) SAN technology components may inadvertently drive away some enterprises that should really be considering this technology.

Furthermore, another insufficient rationale for creating and implementing Storage Area Networks is the possibility of financial savings by itself. Other pooled storage architectures and SANs can be expensive. They also add complexity to enterprise operations and infrastructures. Quite often, in order to improve staff skills and the adoption of robust operating procedures, new processes and technologies are required; as well as, training. Also, other storage systems attached to SANs are more expensive than attached disks on !ow-end servers or just a bunch of disks (JBODs).

An Investment

Today, SAN creation and deployment is an investment, and not necessarily a cost-saving action. As more second-generation SAN adopters create and deploy this technology, more thought is required by the enterprise for the investment rationale; and, demands for improved ROI are growing.

Clear investment payback and total cost of operation (TCO) improvements by enterprises have validated the various SAN buying models presented in this article. It is also plausible that the data may identify the SAN as a major cost-saving technology by early 2003, as more empirical data becomes available and is certified by more users. Thus, as further empirical data is made available, these SAN buying models are being fine-tuned by numerous enterprises.

Open Systems Architecture

Since many enterprises today have adopted an open architecture (a topology-independent approach to SAN design, creation and implementation), not all corporate IT departments have to consider complex Fibre Channel switch or director technology to achieve the benefits of central storage pools. In order to assist in early preparation for cost, benefit, and acquisition approval of new infrastructure technology, the enterprise should create buying and return on investment (ROI) planning models, as part of its general SAN planning methodology. With different topologies, most enterprises have found that ROI has a different payback and impact. Also, for each IT infrastructure, ROI is different. Therefore, in order to help each enterprise design, create and implement the SAN solution that best fits its operational, technical, and financial requirements, the preceding ROI knowledge must be used routinely.


In addition, there are several functional areas that the enterprise must identify in order to demonstrate a valid ROI in business case planning when moving to its first SAN. Not all cases are created equal in terms of measurement, justification, and validation. Much of the business case planning functional areas will depend on the individual enterprise environment. Most of the benefits identified by the enterprise appear for open systems. The reason for this is primarily because these systems tend to have the largest share of data management and scalability problems. And, the other reason is, because they are usually the prime target for pooled storage or consolidation on the SAN. With that in mind, the following are the ROI business cases that an enterprise should use for planning when moving to its first SAN from a DAS environment. All of these cases will be discussed in some detail in Part II of this article:

  • Applications development and testing impact.
  • Avoid upgrade by improving LAN/WAN performance.
  • Backup servers elimination/reduction.
  • Backup windows to eliminate and reduce batch.
  • Bulk data movement through increased I/O performance.
  • Consolidation of Vendors.
  • CPU load on servers reduction.
  • Critical data protection improvement.
  • Current storage life increase.
  • Data area network growth avoidance.
  • Data path availability improvement.
  • Disaster recovery capability improvement.
  • Disk procurement deference.
  • Disk utilization increase.
  • Floor space/data center reduction.
  • General-purpose UNIX and Windows NT servers reduction.
  • Improvement of terra byte (TB)-per-administrator.
  • Management costs as a percentage of storage costs.
  • Migrating or new applications impact.
  • New capabilities for disaster recovery (DR).
  • Non-disruptive scalability.
  • On demand storage.
  • Options for on-line recoverability.
  • Secondary security services.
  • Server clustering support.
  • Server(s) life extension.
  • Server management staff utilization.
  • Storage maintenance reduction.
  • Tape library procurement deference.
    Of course there are other factors to consider, but this list represents those that are highest on the list when it comes to discussing the benefits of a SAN.

    Financial Pay Back And ROI Support

    Just emerging, is empirical data supporting ROI and financial payback for pooled storage architectures (relative to the current status of specific SAN technology and the current technical reference model). However, much SAN ROI analysis may remain theoretical in nature. Most SAN savings will be soft-dollar savings–that is, savings that are less tangible and harder to validate by saving an actual IT budget. Recognizing that normally, no tangible cost savings will be recaptured, these soft-dollar savings are often fuzzy feeling-good numbers that the enterprise’s management should understand and appreciate. Nevertheless, soft-dollar savings should not be underestimated or disqualified from the analysis, because they typically represent the larger percentage of SAN ROI and payback dollars.

    Finally, hard-dollar savings will also emerge from the SAN ROI analysis. Hard-dollar savings are real savings that could be removed from future budgets or operating cost structures.

    Summary And Conclusions

    Many enterprises have recognized new efficiencies when moving from their DAS infrastructures to include a Storage Area Network (SAN). It is these varied efficiencies and benefits that should prompt steps toward the first SAN procurement. SAN creation and deployment should not be undertaken with the heightened expectation that near-term cost savings will always be the result.

    With the preceding in mind, this article presented the justification and business impact analyses that can be completed to show offsetting terms for the necessary new SAN investment from the old DAS environment. Furthermore, in order to assist SAN buyers in determining business value and financial impact when implementing storage area networks, this article also briefly discussed some theoretical approaches that use industry standards and units of measure (where available).

    Finally, this article recommends that a return on investment (ROI)/business case analysis be conducted by an enterprise prior to the first SAN installation. SANs do offer demonstrated areas in which their use can save money for the enterprise. However, these savings will vary with differences in topology and the relevance of hard- and soft-cost savings to the enterprise. Part II of this article provides a structured approach for calculating a SAN ROI. It identifies numerous SAN business planning cases–ranging from increased disk utilization to a reduction and elimination of batch and backup Windows. This case information can help enterprises build strong and accurate business cases for a first SAN creation and deployment.

    About the Author :John Vacca is an information technology consultant and author. Since 1982, John has authored 36 technical books including The Essential Guide To Storage Area Networks, published by Prentice Hall. John was the computer security official for NASA’s space station program (Freedom) and the International Space Station Program, from 1988 until his early retirement from NASA in 1995. John can be reached at


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    John Vacca

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