Implementing tiered storage

From Wikibon

Revision as of 12:48, 12 June 2007

Originating Author: David Floyer

Many organizations are experiencing rapid growth in the amount of information held on computer storage and storage costs are escalating.

Traditional methods of managing storage use either a “one size fits all” strategy, or a "Mix, Match and Manage" approach introducing many different storage pools. The challenge of the first technique is high equipment cost, whereas the latter often brings higher labor costs to manage the multiple storage pools all with different software, services and procedures.

Today's storage technologies span a spectrum from high density, low cost, low performance storage at one end to increasingly sophisticated data management functionality at the other. Creating storage tiers with more granularity with a single management approach begins to address the problems that one size does not fit all and storage pools are hard to manage.

Tiered storage capability

Tiered storage is the process of provisioning different types of storage media based on application requirements. Storage tier choice may be based on performance, cost, protection needed, speed of recovery, and many other considerations. Ideally, a common set of storage services and procedures can be applied as required to each tier, matching application requirements with storage tier characteristics. A more complete description can be found on the WikiBon entry for Tiered storage.

Tiered storage has the potential to reduce the costs of storage and storage management functionality for some applications and improve the performance, availability, and recovery capabilities of others. The primary initial costs associated with a tiered storage implementation include software to manage the environment, implementation expenses, and possibly write-down costs for hardware that will be retired.

Specific operational goals of implementing tiered storage

The likely investment required to implement tiered storage is between $0.5 million to $0.7 million, with an elapsed time of between 6 to 9 months. [Note: These figures assume a Standard WikiBon business model organization with $1B in revenue with 4,000 employees and an IT budget of $40M per year. The scenario assumes that 40 terabytes are installed, with a mixture of high performance SAN, mid-range storage solutions, some direct attached storage, and some NAS]. A successful tiered storage implementation will:

• Allow consumers of storage to optimize the functionality, performance, and cost profile for storage that best fit the business need for each application by providing different tiers of storage.
• Ideally, provide a common set of storage management tools, processes and procedures and services for all the storage tiers, including the ability to dynamically migrate storage to the optimal tier.

The major expected reductions in IT cost will normally include:

• Fifteen percent (15%) reduction in cost of equipment and connectivity (~$200K/year).
• Twenty percent (20%) reduction in cost of storage administration (~$150K/year).

Case studies indicate the major expected business productivity improvements (so-called intangibles) will yield an estimated gain that equates to ~.06% of revenue and normally be derived from the following:

• Business benefits of accelerating time to implement new projects or speed changes (~$200k/year).
• Business value of improving security measured in mitigated losses (~$100k/year).
• Economic benefit of higher performance on user productivity (~$75k/year).
• Business value of improved productivity from reduced application downtime (~$25k/year).

Figure 1 - Tiered Storage Rules of Thumb

In addition to the investment in tiered storage, other potential impacts on an organization include:

• Loss on books for storage equipment and software retired early.
• The business impact of delaying some projects because of resources dedicated to storage.

An analysis of the need for tiered storage is likely to find that a business case including both IT and business benefits will be good (ROI and IRR>150%), while a business case with only IT benefits is likely to be deemed acceptable (ROI