Convergence of SAN, NAS, and IP networks


Next-generation storage networks will combine block- and file-level data access with emerging technologies such as iSCSI-based IP storage.


Without new, more-efficient methods for deploying, managing, and maintaining storage, organizations are at risk of being overrun by the coming storage onslaught. The creation and consumption of data and digital content have exploded as a result of the Internet and associated applications such as e-commerce and rich-media distribution. A Forrester Research survey of 30 Fortune 1000 companies found that the average annual growth rate of data storage was 100%, with the capacity requirements of some firms tripling.

Storage is becoming an increasing percentage of IT spending, and studies have shown that by 2003 storage could consume up to two-thirds of the corporate IT budget. Further, analysts say that for every $1 spent on storage, $0.20 is spent on hardware and $0.80 is spent on storage management.

Clearly, storage is fast becoming a major IT focus. But the issues go beyond the cost of procuring storage. The major challenge for organizations is maximizing storage efficiency to minimize the cost and complexity of deploying and maintaining storage assets. Storage cost of ownership is becoming a key metric of success, and in these leaner economic times, a means of potentially achieving competitive advantage.

Current storage networking solutions such as storage area networks (SANs) and network-attached storage (NAS) have enabled organizations to deploy large amounts of storage more effectively across a variety of users and applications. While these "first-generation" solutions have offered efficiencies and cost savings over traditional direct-attached storage, they represent different approaches that today require organizations to build and manage separate storage infrastructures. The inefficiencies of this approach are forcing a convergence and consolidation of first-generation NAS, SAN, and emerging IP storage technologies in a new generation of storage networking solutions.

First-generation storage networking solutions represent disparate islands-each with a separate set of technologies, storage devices, and management tools.
Click here to enlarge image

Application requirements will continue to drive storage deployment. The size and scope of applications will mandate intelligent storage network solutions that enable organizations to deliver multiple, optimized storage services across a range of users and applications. Cost considerations will drive centralized management of these services, and IT organizations will need to maintain the flexibility to select best-of-breed storage products based on industry standards to ensure compatibility across the enterprise network.

In addition, companies face the challenge of migrating toward next-generation storage networking while leveraging existing investments. This migration will require approaches that improve the efficiency of managing storage resources and significantly reduce the total cost of ownership of storage infrastructure. Economic realities will drive organizations toward a new generation of storage networking approaches that combine the functions and benefits of SANs and NAS, while leveraging existing IP network infrastructure and trained personnel.

Limitations of storage networks

Traditional methods of attaching storage directly to application servers cannot scale efficiently to accommodate ever-increasing storage requirements. IT organizations have begun to migrate to a more efficient method in which storage is connected to host computers via a network. Storage networking has let organizations quickly roll out special-purpose storage servers on existing IP networks and has provided a means to consolidate storage in dedicated networks for improved performance and more-efficient and cost- effective management. Storage networking has also opened up new opportunities for addressing applications such as remote backup, data replication, and disaster recovery.

Vendors have responded to the need for storage networking by promoting two different approaches, each driven by a specific set of end-user requirements. Today, SANs offer a means of networking host servers and storage in a discrete, high-performance network. In addition, almost all SANs use Fibre Channel-an interconnect technology developed specifically to enable the high-speed transfer of block-level storage traffic. Since today's SANs provide a single domain for storage resources in the network, organizations have been able to significantly reduce the expenses associated with managing and maintaining storage.

Next-generation storage networking solutions will converge NAS, SAN, and IP networking for more-efficient management and lower total cost of ownership.
Click here to enlarge image

Another widely used approach is NAS, which addresses the need to deploy storage rapidly in an existing Ethernet/IP network environment. NAS solutions allow computers running different operating systems file-level access to the same set of physical storage.

While these storage networking approaches have gone a long way toward solving problems of storage centralization and scalability for specific types of data access, they fail to offer the levels of efficiency, cost-effectiveness, and ease-of-deployment and management required to address burgeoning demands for storage.

The limitations of first-generation solutions will give rise to a new generation of storage networking architectures that support the convergence of SAN, NAS, and IP networks. While SAN and NAS each address a different set of problems, the reality is that today, many organizations need the benefits of both approaches. This means installing separate solutions, each bringing with it a separate set of technologies, networks (Fibre Channel or Ethernet), storage devices, and management schema. This is not the most efficient and cost-effective approach.

New storage networking solutions will converge these different approaches into an integrated solution that offers all of the respective benefits of SAN and NAS in a single, intelligent, easy-to-manage infrastructure. These solutions will also support a full set of commonly used networking interconnects to enable organizations to choose the most appropriate technology for a given application. Additionally, organizations will be able to introduce these solutions into existing storage networks and ensure interoperability with existing infrastructure investments without expensive "forklift" upgrades.

IP storage

Not surprisingly, the industry has shown an interest in using IP networks for block-level storage traffic. Driving this trend are

  • Increasing Ethernet bandwidth (1Gbps this year, moving to 10Gbps next year);
  • Ubiquity of IP network infrastructures in LANs, MANs, and WANs;
  • Abundance of personnel trained to manage IP infrastructure; and
  • Emerging standards such as iSCSI (the standard specification for SCSI block storage transmission over IP) and related products will enable the creation of SANs using Ethernet/IP networks, as well as the broader distribution of storage across existing LANs, MANs, and WANs.

Ultimately, storage networking will enable IT organizations to build a centrally managed pool of storage that supports both block- and file-level (NFS and CIFS) access. These solutions will provide local and remote data access using standard storage networking connections, including Fibre Channel, Ethernet, or future technologies such as InfiniBand.

As storage networking functions converge and become centralized, organizations will need products that do more than simply move storage traffic over the wire. They will need "intelligent" infrastructure platforms that can process storage traffic of any type to ensure security, optimize performance, and virtualize resources for efficient management across a diverse set of users, customers, and applications.

An intelligent infrastructure merges key storage networking capabilities into a foundation that is central to an organization's storage networking infrastructure. This type of solution acknowledges two fundamental realities that organizations face in their efforts to keep up with storage demand:

  • Most organizations have a diverse set of storage needs and therefore require the ability to deploy multiple technologies in a synergistic and cost-effective manner; and
  • First-generation solutions have evolved as a collection of single-purpose products that, while optimized to address specific point problems, introduce inefficiencies and often limit cost-effective growth.

By leveraging intelligent infrastructure switches, organizations can easily migrate to storage architectures that deliver greater economies and cost savings by consolidating the storage network infrastructure-as opposed to deploying multiple disparate solutions. This approach allows organizations to benefit from centrally managed platforms that deliver a diverse yet synergistic set of capabilities. By supporting Fibre Channel switching and IP networking equipment, "utility switches" will complement existing storage networks by adding intelligent services such as load balancing, storage virtualization, and secure storage provisioning.

These solutions will bring together many of the following capabilities:

  • Unification of file (NAS) services with traditional block (SAN) services, IP networking with storage, Fibre Channel with Ethernet, and LANs, MANs, and WANs;
  • Heterogeneous storage support to allow users the freedom to choose the class of storage most suitable to a given application;
  • Virtualization and secure provisioning to provide individual users or departments with their own private, dedicated share of storage network resources;
  • Management tools for configuring, monitoring, and maintaining all storage services under a common management umbrella;
  • Support for current and emerging standards to ensure interoperability with existing and future storage networking products; and
  • Flexibility to scale performance, connectivity, and capacity independently and on demand with no disruption to data access or applications.

These storage networking platforms will integrate high-performance switches that route traffic between intelligent processing modules. Highly modular architectures are required to offer maximum flexibility to scale resources in any dimension (including performance, capacity, and connections) and support new technologies and capabilities as they become available.

Block- and file-level access

Applications will continue to drive organizational strategies for network storage. Some applications such as online transaction processing (OLTP) require the best performance available. These applications can continue to benefit from SANs that facilitate block-level access to a common pool of storage. Other applications such as engineering change order (ECO) processing have requirements weighted more toward the ability to serve files in a heterogeneous computing environment. Here, a NAS approach providing NT and Unix systems with file-level access to storage over a LAN is a good solution.

Organizations will no longer have to choose between these two approaches because next-generation solutions will support both block and file access to storage and extend this access over standard IP networks. An obvious benefit is that organizations will deploy a single storage network platform to serve multiple types of applications to multiple sets of users throughout an enterprise. And all services whether block- or file-level will fall under a common management domain.

The benefit of converging SAN and NAS capabilities lies in the ability to leverage the strengths of each. IT departments can leverage the advantages of SANs for storage pooling and centralized storage management, and the advantages of NAS for file-level access by heterogeneous clients. Organizations will be able to build a common storage pool that is accessible at either the block or file level over existing IP networks.

Capacity will grow by adding storage resources to the centrally managed storage pool, as opposed to replicating storage and management domains across the network. The result is more-efficient management of resources and the ability to use existing storage and network infrastructures to serve multiple applications.

Virtually all SANs today rely on Fibre Channel as the storage network interconnect. Fibre Channel was developed specifically to connect servers to storage. However, recent advances in technology and industry coalescence around standard storage networking protocols have brought IP storage networks into the limelight. The industry's interest in IP networks as an alternative to Fibre Channel is based on the fact that IP networks are pervasive throughout the world. As such, IP networking brings with it an abundance of supporting equipment, tools, and people trained in managing and maintaining IP networks. The ability to leverage this ubiquitous infrastructure translates into huge cost savings.

Some organizations have invested heavily in Fibre Channel equipment and training to deploy SANs today. As IP storage technology matures, organizations planning future SAN deployment-including companies that have already deployed Fibre Channel SANs-will have a choice of technology. Next-generation infrastructure products will support both Fibre Channel and IP networking, and this flexibility will promote new opportunities for deploying scalable storage networks.

Managing growth

Organizations want the flexibility to choose the most cost-effective solution. A majority of today's SAN and NAS solutions support a single type of storage from a single vendor. Unfortunately, these solutions become limiting as organizations begin to expand capacity. As application requirements evolve, organizations need to expand capacity to match changing application profiles. They typically require more-expensive, high-end storage subsystems to achieve the optimum performance and availability required by mission-critical applications. They also may need to serve departmental and workgroup applications that usually do not justify the expense and overhead of this class of storage.

These types of scenarios force organizations to either add storage that is not matched effectively to the application or deploy separate storage networks for each application. Both approaches are inefficient and costly.

New solutions will provide maximum flexibility by supporting multiple storage types from a variety of vendors. As storage needs increase, organizations need to be able to grow their resources in lock-step. Sometimes this means adding more processing power or more connections or simply more disk storage capacity. Organizations need the flexibility to add any of these resources, at any time, without interrupting user access to storage.

IT departments will no longer have to make either/or decisions between SANs and NAS; instead, they can consider approaches that converge the advantages of SANs, NAS, and IP solutions. These solutions will provide an environment where users and applications can access a common storage pool using block- or file-level protocols across Fibre Channel SANs and IP networks, and comprehensive management services and tools will allow enterprise network storage management. These platforms will complement existing storage networking assets to afford organizations a smooth transition into centrally managed storage networking that can scale cost-effectively to meet ever-increasing business requirements.

Steve Marchesano is director of strategic marketing at Pirus Networks (www.pirus.com) in Acton, MA.

Coming in INFOSTOR...

SPECIAL REPORT: Fibre Channel update:
The move to 2Gbps

Also in the September issue: FEATURE ARTICLES

  • Easing the migration from DAS to SAN
  • Storage virtualization, part 1
  • Building storage area networks, part 1
  • Deploying cost-effective database storage
  • High availability for Windows 2000


This article was originally published on August 01, 2001