Disk array storage considerations as part of TCO strategies

Computer Technology Review, July, 2004 by Rob Peglar

The First Step: Understand the Business Environment in relation to Storage TCO

Information availability drives the success of today's real-time business, its partners, and its suppliers. Empowering businesses with up-to-date and aggregated information has created a new wave of real-time, data-intensive enterprise applications. The dynamic nature the market, competitive challenges, and constantly changing user needs has further intensified the need for IT infra-structures to dynamically adapt and respond to meet business requirements. Furthermore, the sheer diversity of today's information users, many of whom now access information through 24X7 Web portals, has resulted in unpredictable information utilization patterns and processing requirements. Within this dynamic environment, data growth for many organizations, especially those in the small-mid-enterprise (SME) space now exceeds 100% annually, challenging traditional storage architectures' abilities to efficiently and cost-effectively manage and scale the storage infrastructure. Because of these limitations of traditional storage architecture, TCO must be considered carefully as data multiplies throughout the enterprise.

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Server and application architectures have evolved to meet the demands of today's unpredictable, highly distributed, real-time processing environments. Clustered architectures aggregate processing power across application modules, while increasing performance and responsiveness and providing near-linear scale. Clustered application architectures also provide new levels of resilience for application processing across clustered blade or classic server infrastructures. Application clusters also dramatically reduce the operating and capital expenditures associated with data center infrastructures, thanks to the commoditization of hardware and the simplification and dynamic nature of administration.

The Next Step: Evolve Storage Infrastructure Away From Excessive TCO

Today's enterprises benefit from the deployment of clustered processing and application architectures with dramatically increased uptime and resilience, configuration flexibility, and immediate scalability. In contrast, traditional storage area networks (SANs) continue to feature dual-processor, chassis-based, static architectures, which not only limit storage flexibility, but also demand large capital investment risks.

These chassis-bound architectures leverage mainframe-era designs to deliver reliability against unplanned downtime events. The necessity of planned downtime to expand volumes, change RAID levels, or alter overall storage configurations results in minimal configuration flexibility. Additionally, the scalability of capacity and performance is limited, based on the expansion capabilities of a fixed two-controller architecture. Monolithic architectures do not allow organizations to protect investment and take advantage of technologic advances, for example, with regard to drive capabilities, since traditional SANs require that all drives within the system be identical and controller upgrades require downtime events of the entire storage subsystem.

This limits overall storage responsiveness and increases storage operating expense (OPEX) and total cost of ownership (TCO). Modern storage architectures must evolve to address issues including:

* Traditional SAN architectures require significant acquisition and deployment investments, thanks to their monolithic, tightly integrated design. Traditional SAN architectures inject dual hardware expense and management complexity for standalone, single-chassis protection against unplanned downtime. Even so, these large capital investment (CAPEX) outlays are often overshadowed by the significant expense involved in configuring and deploying the SAN. SAN deployment and/or reconfiguration usually requires expensive vendor professional services, with the result that upgrade decisions/pathways are often deferred because of the high cost involved. This delay in availability of critical applications has significant financial and competitive implications.

* Traditional SAN architectures severely limit the responsiveness of the computing infrastructure. Configuration, deployment, management and maintenance are static and complex in nature. Traditional SAN architectures require significant planned downtime to change or upgrade storage, server, or application infrastructures. These architectures also require dual-pathing software on the host to enable SAN interconnectivity and to prevent storage disruption. This software adds significant time and management overhead, while preventing the true server and storage independence promised by the concept of SAN.

With traditional architectures, desired infrastructure changes are often postponed for weeks or months, and then implemented during planned outages at the expense of overall information availability. Planned downtime accounts for over 80% of data unavailability, yet is accepted today as "status quo" within the industry. In today's Web-based environment, the impact of information unavailability reaches far beyond internal users--impacting revenue generation, just-in-time (JIT) supplier delivery, and partner performance.