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IP Storage Switches Open Up Storage Networking.

Storage networking helps companies build, manage, and maintain an ever-increasing amount of data. Over the past few years, IT departments have begun to adopt and deploy data-intensive storage networks using a variety of technology and equipment, with most implementations based on Fibre Channel. However, enhanced storage networking implementations based on the ubiquitous Internet Protocol (IP) now have emerged. This profound change--combining storage devices with IP networking--brings a new level of interoperability and reach to storage networks.

IT managers are well aware of the power and reach of IP networks, which have been widely accepted for Local Area Networks (LANs) and Network Attached Storage (NAS), but thought unfeasible for Storage Area Networks (SANs). So today's SANs have no native IP end systems. Instead, they are comprised of parallel SCSI and Fibre Channel devices, including host bus adapters (HBAs) in servers and interfaces to external RAID and tape libraries. These end systems are stable, interoperable, and well understood throughout the IT community. More recently, Fibre Channel networks have been added to the storage mix, but the lack of switch interoperability among Fibre Channel switches and the need to learn new Fibre Channel routing protocols, have limited the deployment of Fibre Channel switch networks.

As these new IP storage networking products emerge, IT managers will be able to capitalize on the flexibility and simplicity of storage networking with IP and Ethernet, maintain compatibility with the emerging IP storage standards, and provide seamless integration with existing storage infrastructure such as parallel SCSI and Fibre Channel HBA end subsystems.

Background Of Storage Networking

With storage requirements ever increasing in IT organizations, storage networks have emerged as a useful mechanism to eliminate dedicated links between servers and captive storage devices. Applying similar principles to those used in LANs, a SAN helps IT mangers maintain flexibility in their storage configurations. With a SAN, new storage devices can be easily added without downtime, storage subsystems can be shared across numerous servers, backup operations can be offloaded from the LAN, and operations such as remote mirroring can be implemented with relative ease. At the time the SAN concept started to take hold, the only technology available to implement was Fibre Channel.

In their simplest form, Fibre Channel networks can be just cables between Fibre Channel host bus adapters and storage devices. Fibre Channel switches also can be used to create a SAN, a second network that handles block-based data, rather than file-based data, as a LAN does. This dual network implementation burdens IT managers with two network cost structures--one for their LAN, based on Ethernet and IP, and one for their SAN, based on Fibre Channel.

Fibre Channel also has no native extensions for long distance storage applications, such as remote backup to another facility. Fibre Channel requires costly and awkward solutions such as leasing dedicated dark fiber optic lines and using DWDM technologies.

Fibre Channel end systems such as servers and storage subsystems recently have achieved a high degree of interoperability based on the standardized serialization of the SCSI command set known as Fibre Channel Protocol (FCP). However, Fibre Channel switches still suffer from the lack of interoperability--especially as compared to the interoperability of the switches and routers used in proven IP and Ethernet networks. A solution that leverages existing Fibre Channel devices, and transfers the networking aspects of SANs to IP and Ethernet, can create end-to-end interoperable storage networks by leveraging the best from both the storage and networking worlds.

The Next Generation Storage Network--Gigabit Ethernet And IP

Gigabit Ethernet has become the de facto high speed-networking link for corporations, service providers, and a new class of carriers called ELECs (Ethernet Local Exchange Carriers). Built upon the well-known and time-tested Ethernet protocol, with the robustness and integrity needed for gigabit speed transmission, Gigabit Ethernet has the capability to handle storage traffic at speeds that meet or exceed those of Fibre Channel.

Leveraging Gigabit Ethernet and IP technology for storage networks allows IT managers to use the wide range of existing IP and Ethernet knowledge and training. And, since both SANs and LANs can be based on the same technology, IT managers can more flexibly provision their networking resources. SANs still can be separate from LANs, but the technology and management are united--saving time and cost in deployment and maintenance. IT managers can choose to support both LAN and SAN traffic on one set of networking hardware, isolating them to separate VLANs.

Standardizing on IP and Ethernet for the storage network fabric, IT managers can tap into campus, metropolitan, and wide area networks with readily available, dedicated or provisioned IP bandwidth. This avenue, previously unavailable for Fibre Channel SANs, opens wide-ranging possibilities for data distribution, replication, backup, and recovery.

IP Storage Protocols And New IP and Ethernet Storage Devices

Because of the limitations of Fibre Channel networking and Fibre Channel switch technology, industry vendors recently have banded together to guide the direction of the next generation in storage networking--IP storage. This includes standardized implementations with protocol specifications such as iFCP and iSCSI, along with iSNS, a protocol to handle name services and discovery for storage devices linked to IP networks. These protocols are under review with the Internet Engineering Task Force (IETF) and will likely form the core of the IP Storage protocol suite.

Some of the new IP protocols, such as iSCSI, focus on the deployment of new end storage devices with Ethernet and IP interfaces, allowing users to build end-to-end systems based on Ethernet and IP technology. While this remains an ideal goal, it is predicated on an end-system upgrade from current parallel SCSI devices or Fibre Channel. For new installations, this is a logical path. However, for installations where numerous storage devices currently exist, this solution alone presents potentially costly and awkward storage system changes.

From Today's Storage Environment To TheFuture-Using IP Storage Switches

Fortunately, there is no need to wait for these new standards and a new class of storage end devices to emerge. IT managers can immediately leverage the power of IP and Ethernet in the core of their storage networks while maintaining full compatibility with end systems based on SCSI or Fibre Channel. This implementation takes place with some of the new IP storage switches.

Quickly emerging as the next wave of storage networking switches, IP storage switches provide interfaces to SCSI and Fibre Channel, as well as Gigabit Ethernet and IP. As an example, a server with a Fibre Channel HBA can plug directly into an IP storage switch as if it were talking to a regular Fibre Channel switch. The HBA remains with its current drivers, and the application software remains unchanged. The IP storage switch handles the flow of the data to its destination. With data directed towards a local Fibre Channel storage device connected to the same switch, it is passed through the IP storage switch as Fibre Channel data. The receiving storage device also connects to the IP storage switch via Fibre Channel, using its existing interface and firmware, and eliminating the need for an upgrade.

But the real power of the IP storage switch comes with the next step. If data from the HBA needs to reach another switch, or travel over a network (campus, metropolitan, or wide area), the data is converted to the worldwide network transport and language of choice--IP and Ethernet. This transformation, handled by the IP storage switch itself, with no overhead to the servers or end systems, opens up an infinite number of configurations, applications, and storage solutions that previously were restricted from the isolated SAN islands built with Fibre Channel.

Figure 1 shows a storage network that supports existing storage devices (Fibre Channel HBAs and RAIDS, along with SCSI storage) and common, widely available IP and Ethernet networks.

Investment Protection--Existing And Future Infrastructure

As described in the previous section, some of the new IP storage switches allow IT managers to incorporate all existing Fibre Channel and SCSI end devices (both servers and storage end systems) into an IP and Ethernet storage network fabric. This provides investment protection of the legacy storage infrastructure.

These IP storage switches, with their ability to handle Ethernet as well as Fibre Channel and SCSI interfaces, also can incorporate new storage end devices when available, such as IP storage adapters based on iSCSI. As these devices come to market, IT managers can rest assured that their investment in an IP storage switch infrastructure will provide a smooth transition path. As the new IP storage protocols mature, vendors providing IP storage switches will be able to maintain full protocol compatibility via software upgrades.

Scaling Storage Networks With IP And Ethernet

There is no better example of a scalable infrastructure than the Internet. This global network proves that the simple, well-designed Internet Protocol (IP) can scale to enormous proportions. IT managers, in scaling their storage networks, now can make use of the same protocol that helped the Internet scale to its current proportions. Figure 2 demonstrates the use of IP and Ethernet in scaling a large storage networking fabric.

By using IP and Gigabit Ethernet for the storage networking fabric, IT managers can leverage a wealth of products, technology, staff, and resources. For example, core switches for the storage network could be the same high-density Gigabit Ethernet switches currently used in the enterprise data center. Additionally, routing protocols leverage mature, time-tested implementations such as OSPF. This leads to shorter deployment times for large storage networks, reduces costs by use of common enterprise technologies, and provides the ability to scale rapidly with the same technology that helped build the Internet.

Unified SAN-MAN-WAN IP Storage Networks

Using one networking technology for both the storage network fabric and the SAN to SAN interconnect permits the use of a unified management system that simplifies deployment, reduces cost, and provides IP visibility across the entire infrastructure.

Enterprises and service providers alike can centralize their storage management, services, and network features based on IP. This seamless integration is highlighted in Figure 3.

Achieving The Benefits Of IP Storage Networks--Today

IP storage switches provide the infrastructure IT managers need today to integrate Fibre Channel and SCSI storage end devices with IP and Ethernet networks. This implementation can take place with equipment available today, maintaining full compatibility with existing storage management applications, but also by releasing the power and reach of IP networks to storage. IP storage switches also offer full compatibility with emerging IP storage specifications--providing both past and future investment protection for IT managers.

Gary-Orenstein is the director of marketing at Nishan Systems (San Jose, CA).
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Title Annotation:Technology Information
Author:Orenstein, Gary
Publication:Computer Technology Review
Geographic Code:1USA
Date:Apr 1, 2001
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