SANs Seek Adoption by SMBs

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The high cost of SAN-attached storage, switches, and HBAs has been a barrier to entry for many medium and small companies. Small and medium-sized businesses (SMBs) have the same basic requirements for data availability, performance, and safeguarding of data that large enterprises have secured via SAN technology, but they often lack the budget or expertise (or both) to implement enterprise-class SANs. Consequently, these companies continue to spontaneously accumulate additional servers and direct-attached storage to meet their growing data needs and eventually pay a penalty in terms of higher administrative overhead and inefficient storage utilization.

The cycle of reactive acquisition of direct-attached storage (DAS) and servers to front-end it, followed by increased cost for administration, is being broken by the introduction of new, lower cost SAN technologies. These include often over-hyped technologies such as iSCSI , but also include new classes of economical storage arrays and cost-reduced Fibre Channel and IP storage switch products.

The availability of lower cost, shared storage solutions is further validation of the maturity of SAN technology. Nurtured in the relative affluence of large data center budgets over the past decade, SAN solutions are now poised to penetrate the vast middle market and eventually displace direct-attached storage. Lower costs and familiarity with the basic value proposition of SANs will encourage further adoption, which in turn will facilitate even lower costs over time.

Where Information Lives More Economically

Traditional storage solutions providers such as EMC and HDS are reaching out to the SMB market with smaller disk arrays that enable modular growth and combine economy with some enterprise-class storage functionality. The EMC CLARiiON series solutions, for example, offer advanced options such as disk-to-disk (D2D) data replication and data copy, as well as the ability to scale to large capacities. Resold through Dell, CLARiiON storage is often bundled with servers and a SAN switch to provide a preconfigured SAN solution to streamline deployment.

Likewise, the HDS 9500 series modular storage arrays enable mid-tier customers to incrementally grow their storage capacity over time. Optional storage virtualization software can further simplify storage allocation and management.

Although large enterprises may also benefit from the economy of these smaller solutions, it is unlikely that low-cost storage systems will pose a threat to more expensive, high-end systems. Data centers still require the higher availability, performance, and self-diagnostic (e.g., phone home) capabilities of more expensive arrays for mission-critical applications.

Low-cost SAN storage is also being introduced by a number of start-ups. To avoid competing in the already crowded enterprise storage market, these new vendors are focusing on the as yet untapped broad middle market and are porting sophisticated SAN features to more affordable storage platforms. By using Serial ATA (SATA) or Serial Attached SCSI (SAS) disks for back-end storage and efficient disk controllers that interface to iSCSI or Fibre Channel, these solutions are putting “inexpensive” back into the original definition of RAID (which, in the pursuit of margins, was changed to redundant array of “independent” disks).

A new storage player, Compellent, has gone a step further by separating the storage controller engine from both outbound interfaces and back-end storage. This offers the flexibility to use iSCSI, Fibre Channel, or any future transport protocol for external access, and leverage traditional SCSI, Fibre Channel, SATA, or SAS disks. Integrated storage virtualization also makes it possible to economically implement information lifecycle management (ILM) by creating different classes of storage under automated, policy-based data management.

Other start-up companies such as StoneFly Networks are focusing on IP SAN technology under the banner of SANs for the masses. With the ability to integrate a customer’s existing SCSI storage assets with an iSCSI front end, and layer in basic storage virtualization for storage pooling and replication, these solutions are applying the state of the art of SAN technology to low-cost platforms that even small companies and departments can afford. While large enterprises have funded the technical evolution of SANs, the resulting benefits can now be shared by all companies, regardless of size.

Page 2: Calling All Servers

Continued from Page 1

Calling All Servers

Despite having invested millions of dollars in their SAN solutions, even large data centers often cannot afford to attach every server to shared storage. The barrier to entry for second-tier servers is simply cost. Even though overall administrative overhead can be reduced via SAN attachment, putting a $1500 Fibre Channel host bus adapter into a $3000 server is difficult to justify. In addition, the per-server attachment cost necessarily includes a corresponding per-port cost at the Fibre Channel switch or director.

So while mission-critical business applications are typically supported on high-end servers with redundant Fibre Channel HBAs to redundant SAN switches or directors, a company may still have less critical applications driven by hundreds (or in some cases, thousands) of low-end servers with direct-attached storage. These Wintel platforms running NT or Linux represent significant administrative overhead in terms of server code maintenance, over- and
under-utilized storage capacity, and inefficient backup operations.

Integrating second-tier servers for large enterprises and accommodating economical server attachment for mid-range firms is now feasible with iSCSI technology. Since the applications on such platforms are typically less demanding, Gigabit Ethernet may be used to aggregate multiple servers over a single switched link.

Excluding the cost of the iSCSI switch port, the per-server attachment cost may be essentially zero if an iSCSI device driver (available for download from Microsoft and other vendors) is used on a standard Gigabit Ethernet or Fast Ethernet NIC (or range from $300 to $600 if a dedicated iSCSI NIC is used).

Depending on the fan-out ratio of iSCSI servers to iSCSI switch port, the cost of an iSCSI-to-Fibre Channel gateway can be amortized over tens or hundreds of servers. For low volume storage applications, this provides an economical means to leverage the benefits of SANs, including centralized storage management and streamlined SAN-based tape backup.

Although iSCSI is still not widely deployed, it is already putting pressure on Fibre Channel HBA pricing. To cover their options, most traditional HBA vendors have concurrent projects for both iSCSI adapters and new, lower-cost Fibre Channel HBAs. New HBAs in the $500 price range will lower the barrier to entry for conventional Fibre Channel SANs, although customers will still have the ability to mix higher performance HBAs for some servers with iSCSI attachment for others in the same SAN environment.

Multi-protocol Fibre Channel and IP SANs are enabling customers to apply the appropriate technology to service business applications based, not on technical considerations, but on the cost and availability criteria that align with business objectives.

Page 3: In Search of Durable but Low-Cost Fabrics

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In Search of Durable but Low-Cost Fabrics

In combination with economical storage and economical server connectivity, SAN interconnects are the third component facing cost reduction. After enjoying years of high margins on fabric switches, traditional Fibre Channel switch vendors are aggressively moving towards entry-level switches to service the mid-tier market and enterprise branch opportunities.

McDATA , for example, has introduced a low-cost 12-port Fibre Channel Sphereon switch based on a single ASIC that can be economically expanded in 4-port increments. This solution enables a small business or enterprise branch to install a single platform while only paying for additional ports as needed over time.

Lower cost IP storage gateways such as the Eclipse 1620 are also being introduced for mid-tier applications that link modular Fibre Channel storage with iSCSI hosts. Pending the arrival of more native iSCSI storage arrays, IP storage gateways enable customers to build economical SAN solutions that exploit the lower cost of Ethernet and new lower cost Fibre Channel modular storage. In addition, tape vendors such as SpectraLogic are shipping both iSCSI and Fibre Channel tape subsystems, giving the customer the flexibility to select which interface best suits their fabric needs.

Making SANs available and affordable for the broad small and medium business market is the fulfillment of a central goal of storage networking: to make shared storage ubiquitous and more easily deployed. Lower cost iSCSI and Fibre Channel products will foster SAN adoption by tens of thousands of additional businesses, which will in turn stimulate new opportunities for SAN innovation and further cost reduction.

This scenario is what is supposed to happen with viable technologies. Once the tough technical issues have been resolved and a technology has proven its end-user value, its spread throughout the user community can be very rapid — if the price is right.

Tom Clark

Director, SAN Technology, McDATA Corporation

Author: Designing Storage Area Networks Second Edition (2003) (available at, IP SANs (2002) (also available at


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Tom Clark

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