Towards Open Storage Networking

The demand for storage capacity is surging, fueled by the growth of the Internet and the rising demand for online access to data. The ability to move and access data has become a mission-critical capability for every enterprise. CIOs are under increasing pressure to improve data management and reduce total cost of ownership.

The predominant strategy is the move toward networked storage. The storage industry is driving this move with a multitude of innovative storage networking technologies that will add significant capabilities to corporate network architectures. Networked storage is making the revolution in data storage inevitable – and the statistics on storage networking bear that out.

Storage networking, whether network attached storage (NAS) or storage area network (SAN), has become essential to mission-critical IT environments. IDC estimated in a July 1999 report that the storage market in Canada could grow to about $4.3 billion by 2003, of which about $1.5 billion is external storage. Moreover, networked storage solutions are driving all the growth in the Canadian market and are predicted to account for half of enterprise storage revenues by 2005.

The numbers are positive, but in the minds of IT executives the projected growth for networked storage doesn’t paint the full picture. CIOs need some clarification of specific issues in networked storage. This article looks at the capabilities and benefits of networked storage, as well as the debate over network attached storage (NAS) versus storage area network (SAN) technologies. There is a strong belief that the future of networked storage will see a convergence of NAS and SAN, a union that will provide a stronger unified solution to the NAS/SAN debate and pave the way for the ultimate goal: open storage networking.

The Benefits of Networked Storage

Network-attached storage differs considerably from the traditional server-attached storage model that dominates the Canadian storage sector. For CIOs, the burning question is: what are the major benefits of an investment in a storage network architecture? The answer is threefold. Once the decision is made to grow, IT executives can architect shared storage pools that can scale seamlessly. Second, these networks will greatly reduce restore and back-up times by leveraging on-line archives and new types of secondary storage media. Finally, IT managers enjoy far greater manageability of data, because they control their databases from a single central point. This combination of scalability, faster recovery and backup, and manageability inevitably reduces the total cost of ownership of data storage. However, before an IT executive can make a decision to move towards networked storage, the executive should explore the debate that rages between NAS and SAN.

Narrowing the gap between NAS and SAN technologies

A NAS system is essentially a plug-and-play storage solution based on standard IP networking architecture and attached to a local, metropolitan, or wide area network. Its design eliminates server bottlenecks on heterogeneous networks by providing cost-effective storage and file-sharing. SAN is best described as the vision of an open, scalable, fibre-channel architecture that interconnects storage systems, backup devices, and servers. It absorbs LAN traffic to improve network performance.

In network attached storage, a single central file system resides in the architecture of the NAS appliance and controls data storage. In a SAN, the file systems are part of the operating systems that reside on multiple servers. Multiple servers implies that data must be stored in a variety of file systems and formats, which make true data sharing a challenge.

Both NAS and SAN offer significant performance advantages over traditional server-attached storage. Despite this, CIOs often see NAS and SAN as competing or mutually exclusive technologies. The truth is, in a networking environment SAN and NAS are complementary and interoperable, and each has its place in corporate network architectures. For CIOs to understand where these technologies are headed, we have to examine another trend in storage networking technology – convergence.

Why SAN and NAS Are Destined to Converge

CIOs are in search of the ideal storage networking solution, but they also need to improve the operating costs of their business solutions. They will be among the first to drive the convergence of NAS and SAN. Distinctions between NAS and SAN will eventually dissolve, bringing the two together as parts of a single solution. Here are some of the issues currently affecting NAS and SANs:

    NAS is perceived by many industry pundits as being not as scalable as SAN. (NAS can be readily scaled by adding capacity up to multiple terabytes or by adding multiple NAS appliances on the network.)There is a lack of fully functional fibre-channel SANs because interoperability standards remain undefined. In the meantime, gigabit Ethernet SANs have been introduced to provide a more standardized approach to SAN architecture.With multiple vendors and standards, the storage industry faces the challenge of incorporating SANs into a coherent strategy.

A powerful force driving convergence is that CIOs want at least a five-year return on their technology investments while leveraging existing infrastructure investments in human resources, software, servers and networking. Market pressure will move the industry to accommodate these executives.

The rapid rise in networking speed as depicted in the diagram (pg. 42) favors NAS-SAN convergence. Network speeds are now surpassing storage speeds, blurring the line between NAS and SANs from the standpoint of underlying technology. Customers will soon begin to focus more on the value proposition of storage networks and worry less about gigabit Ethernet vs. fibre channel architectures (the key NAS/SAN differentiators.)

Another trend favouring convergence is the open standards initiative of Direct Access File System (DAFS), sponsored by a large consortium of companies (see DAFS eliminates storage input/output latencies by using direct memory access operations between servers and storage memory archi-tectures. DAFS will blur the lines between NAS and SAN even further because it is aimed primarily at the storage network environment and is agnostic to gigabit Ethernet or fibre-channel mediums.

The storage networking technology built around this convergence trend will contain both NAS and SAN technologies in the same product. Any other approach would be less than optimal because companies are not likely to buy two products when one will do. Picture this solution as an intelligent box: on one side are storage technologies and storage protocols to manage disk systems. On the other side are network-oriented protocols for delivering the data from storage to the outside world, including database servers. These same network protocols are used to provide high-speed access to a common automated tape library. This is true cost-effective NAS-SAN convergence, and it exists today.

Open Storage Networking:

The Catalyst for Convergence

Perhaps the most powerful force driving NAS-SAN convergence is open storage networking (OSN) – based on the concept that linking pools of storage with networking technologies gives companies the data they need whenever they need it, with perfect data integrity. The OSN design allows companies to construct data access and management solutions that integrate legacy equipment, as well as new and emerging storage and networking technologies. CIOs can focus on business problems and opportunities – not on evaluating, testing, and integrating new technologies.

The industry is now using OSN to enhance the connectivity layer of SANs and combine them with the power of NAS to deliver an improved storage network solution. The solution architecture spans both NAS and SAN hardware and software technology, and incorporates a powerful data management capability to eliminate the shortcomings of both NAS and SANs.

The storage network of the future will most likely be based on open standards, protocols, and technologies that are plug-and-play interoperable and can be combined to match an IT executive’s needs.

In the end, perhaps the best news for the CIO is that storage solutions are becoming simpler. The enterprise’s move toward networked storage means data management with greater scalability, faster recovery and backup, and a reduced total cost of ownership.

NAS vs. SAN is becoming less of an intellectual struggle as the two technologies, once seen as separate storage solutions, are increasingly being viewed as complementary. The debate is giving way to a model of open storage networking. The OSN concept makes data-sharing across networks practical, simple and reliable. It uses industry-standard protocols and integrates best-of-breed solutions. All the necessary data management hardware and software is available today and deployed at many companies that are enjoying the benefits of OSN.

As awareness of open storage networking increases, CIOs will be looking for solutions that deliver the best of NAS and SAN – but without the limitations of each.

Jeff Goldstein is General Manager of network file storage and content delivery firm Network Appliance Canada, Ltd., Mississauga, Ont. He joined the company from Data General Canada, a division of EMC, where he served as Canadian president and general manager. Mr. Goldstein received a Professional Engineering Designation in 1987, and he holds a B.S. in engineering from the University of Waterloo.