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What are the key differentiators in SAN switches and adapters?

Posted on November 01, 2008

By Kevin Komiega and Dave Simpson

Unlike the market for, say, Fibre Channel disk arrays, the markets for Fibre Channel switches and host bus adapters (HBAs) are not crowded. In both cases, two vendors essentially comprise a duopoly in terms of market share: Brocade and Cisco in switches, and Emulex and QLogic in HBAs.

Despite, or perhaps because of, the paucity of players, each vendor goes to great pains to differentiate its products from its competitors' offerings. For this article, we asked representatives from the leading Fibre Channel switch and HBA vendors to briefly outline what they think are their key product differentiators, and what the benefits are to end users.

SWITCHES

The Fibre Channel switch market has evolved well beyond speeds, feeds, and port counts. Among Brocade, Cisco, and QLogic, customers can buy fabric switches with as few as eight ports and up to as many as 256 ports and more in director-class products.

Each of the switch vendors supports 8Gbps Fibre Channel, but the mantra seems to be “migrate at your own pace.” Most 8Gbps support can be activated for a license fee so users can buy the latest and greatest switches now, but do not have to commit to 8Gbps premiums, which are slightly higher than the cost of today’s 4Gbps technologies, until the need arises.

Some of the key advancements in Fibre Channel switching have been in the areas of management, support for virtual servers, and fabric-based services.

Now that it has completed the integration of hardware and software platforms obtained through the acquisition of McData, Brocade is focusing on Adaptive Networking services, a set of fabric-based applications to help improve server and storage utilization, optimize network and application performance, and increase security.

Marty Lans, senior director of data-center marketing at Brocade, says the physical network takes a backseat to network management technologies that impact flow control, quality of service (QoS), and application mobility as explosive adoption of virtual servers continues to stress the fabric.

Adaptive Networking services comprise a suite of tools for optimizing fabric behavior and ensuring bandwidth availability for applications. These tools include QoS, Ingress Rate Limiting, Traffic Isolation, and Top Talkers. Another feature, dubbed Integrated Routing, allows users to connect switches in different fabrics.

Brocade’s switches feature native support for expansion ports (E_Ports), which are used to connect to another Fibre Channel switch or bridge device through an inter-switch link. E_Port interoperability across Brocade Fabric OS (FOS) and M-Enterprise OS (M-EOS) devices and fabrics allow Brocade switches to connect to other E-port-capable devices to support SAN scaling.

The company’s switches use a non-blocking architecture with as many as 40 ports concurrently active at 8Gbps (full duplex) with no over-subscription, providing an overall bandwidth of 320Gbps. In addition, enhanced Brocade ISL Trunking enables a single logical link at up to 64Gbps of data throughput.

Brocade also touts power efficiency as a key differentiator. For example, the Brocade 5100 switch consumes less than 2.5 watts of power per port and features consolidated power and fan assemblies to improve environmental performance and reduce overall ownership costs.

  

Brocade’s Data Center Fabric Manager (DCFM) software can be used to manage switches, HBAs, and fabrics.

Most recently, Brocade began shipping Data Center Fabric Manager (DCFM) 10.0 software, which is a unified storage network management application that manages the SAN from ports on networked storage systems to HBAs attached to physical or virtualized servers (see figure). DCFM combines McData Enterprise Fabric Connectivity Manager (EFCM) and Brocade Fabric Manager into a single fabric management application.

The company recently began shipping a pair of Fibre Channel encryption products: the stand-alone Brocade Encryption Switch and the FS8-18 Encryption Blade for the company’s DCX Backbone chassis (see “Brocade ships encryption switches,” p. 8). The stand-alone encryption switch is a 32-port, auto-sensing 8Gbps Fibre Channel switch, while the FS8-18 offers the same speeds and encryption services in a 16-port blade. Both models provide up to 96Gbps of encryption processing power and work with key management systems from several vendors to secure data “at-rest.”

Cisco’s MDS 9000 Storage Networking platform has been in place since 2002. While the features and functions of the MDS family have changed dramatically through plug-in modules, speed upgrades and software enhancements, the hardware platform itself has remained intact. Platform consistency is a key differentiator, according to Rajeev Bhardwaj, senior director of product management for Cisco’s Data Center and Switching Technology Group (DCSTG).

Bhardwaj says the MDS family has not changed, it has adapted—an important factor in preventing costly forklift upgrades in order to take advantage of new technologies such as 8Gbps connectivity.

Cisco claims advantages in the areas of support for QoS and security for virtual server environments and the inherent data-protection capabilities of the MDS family, including replication, snapshot technologies, and support for serverless backups—all in the fabric.

Bhardwaj also says Cisco was first out of the gate with end-to-end SAN virtualization because of its Virtual SAN (VSAN) technology, which was named by the American National Standard Institute (ANSI) as the industry standard for deploying Virtual Fabrics. Cisco VSANs segment a single, physical SAN fabric into many logical, completely independent SANs (see figure ).

Cisco’s VSAN technology segments physical SAN fabrics into independent logical SANs.

The company’s ability to put storage applications into the network fabric spawns from the Cisco Service-Oriented Network Architecture (SONA), a three-tier architecture that includes network infrastructure, management services, and an application layer. In its entirety, the service-oriented approach is aimed at making it easier to deploy heterogeneous storage applications in the fabric.

Bhardwaj also claims Cisco was first to enable fabric-based encryption on the MDS platform with Storage Media Encryption (SME). The SME feature enables management of data encryption across multiple types of heterogeneous SAN-attached storage devices, including disk arrays, tape devices, and virtual tape libraries (VTLs). Bhardwaj claims that encrypting data in the fabric helps companies secure data on storage devices that lack native encryption capabilities.

Some other Cisco features include an on-demand port activation license, integrated IBM Fibre Connection (FICON) connectivity support, and a Quick Configuration Wizard that quickly creates a SAN environment for SMB applications. The wizard allows server access to storage in a single step.

In recent months, Cisco has also consolidated its network management platforms. The company changed the name of its SAN-OS operating system to NX-OS to accommodate the company’s new line of Nexus switches, designed to bring unified networking based on 10Gbps Ethernet (10GbE) to the data center. Cisco’s ultimate goal is to develop a single operating system that will support a unified fabric combining both LANs and SANs. In addition to support for 8Gbps performance, NX-OS for the MDS platform also includes policy, visibility, and diagnostic tools for managing both physical and virtual server environments. The NX-OS is the foundation for Cisco’s SAN services such as QoS and security for virtual machines.

The third player in the Fibre Channel switch market, QLogic, hangs its hat on value. Marty Holmes, senior product manager for switches with QLogic’s Network Storage Solutions Group, says each of the company’s SANbox 5800V switches ships with all four 10Gbps stacking ports active by default. This cost-saving feature means basic inter-switch link (ISL) is now included with the product.

Every time a switch is added to a fabric, it results in a diminishing return because it must be connected to every other switch on the SAN. The more ports used for ISLs, the fewer available for storage devices.

Holmes says competitors’ non-stacking edge switches force users to reserve ports for future ISLs or risk disruption during expansion as new switches must “steal” device ports from existing switches. With the 5800V, ISL bandwidth provisioning is automatic, enabling the addition of new switches to a stack at any time without affecting the SAN. Up to six switches—120 device ports—can be stacked and managed as a single unit using QLogic’s switches.

QLogic has also increased the speed of its stacking ports from 10Gbps to 20Gbps—without additional cost. The included stacking ports add an extra 50Gbps bandwidth per switch, which is the equivalent of six extra 8Gbps Fibre Channel switch ports. When upgraded to 20Gbps, the same ports provide more than 100Gbps of extra bandwidth, or the equivalent of 12 extra 8Gbps ports per switch.

Given the consensus that 2Gbps and 4Gbps performance is good enough for now, QLogic is offering a phased “pay as you grow” migration to 8Gbps. Holmes says the 5800V helps users defer migration costs by allowing them to install a future-ready hardware platform, without paying for bandwidth before they need it.

The company’s ISLs are auto-trunking by default, which is another key feature, according to Holmes. Bandwidth capacity from multiple physical ISLs is pooled in a single high-speed pipeline. Instead of becoming queued and trapped within individual pathways, traffic is interleaved and load-balanced to fill the entire pipeline, resulting in faster storage access and application performance for users.

QLogic’s trunking implementation occurs automatically, with no need for manual configuration. Trunked ports do not need to be sequential, and up to 128 ISLs can be included in a single trunk. Trunks will even occur automatically across multiple switches. As long as the paths are the same length, traffic will be evenly distributed for maximum throughput.

QLogic’s cost savings go all the way down to the cabling. The company’s switches will work with any vendor’s SFP transceivers, while Holmes says some competitors require customers to buy their own, branded SFPs.

Support for virtual machines is on the horizon. QLogic plans to announce vFabric, a technology designed to simplify the administration and control of growing SANs while maintaining the cost benefits of shared resources. All of QLogic’s 8Gbps products will support the new vFabric virtualization platform, which will become available to customers as a future software release. —Kevin Komiega

Host bus adapters

On the HBA front, the latest advancement is support for 8Gbps Fibre Channel, and most of the differentiation emphasis centers on ease of use/configuration and, more importantly these days, features that optimize I/O in virtualized environments.

Emulex, for example, is quick to extol its role in the development of the N_Port ID Virtualization (NPIV) standard and its breadth of platform support for NPIV, which includes virtually all virtual-server operating systems (including Microsoft’s Hyper-V), as well as conventional operating systems, including Solaris. The company also claims that it supports more virtual ports per HBA than its competitors.

For end users, the key benefit of NPIV, according to Scott McIntyre, Emulex’s vice president of product marketing, is that it enables administrators to maintain their SAN management best practices and tools as they move from physical to virtual environments. NPIV gives a virtual machine a virtual World Wide Name (WWN) so that users can, for example, zone virtual machines separate from other virtual machines on the same physical server. NPIV also enables LUN masking and mapping on virtual machines, as well as other functions.

Emulex also touts the scalability and ease-of-use of its HBA management tools, exemplified by its HBAnyware software, which enables administrators to manage all Emulex HBAs across an enterprise from a single pane of glass, including automating tasks such as driver updates and firmware downloads (see screenshot).

Emulex’s HBAnyware software enables administrators to manage adapters across an enterprise from a single console.

In addition, Emulex claims users can install and configure its Fibre Channel HBAs in only seven steps, in fewer than 15 minutes.

Emulex also highlights its common driver and firmware architecture, which spans multiple generations of HBAs—and converged network adapters (CNAs) based on the Fibre Channel over Ethernet (FCoE) standard—and the ability to manage all devices from a single console.

The company also points to the CPU efficiency, or CPU effectiveness, of its HBAs, a measure of how much of the I/O load an HBA can handle as a percentage of CPU use. For end users, the benefit of CPU efficiency is that it enables them to run smaller, or fewer, servers and/or run more virtual machines per CPU core.

Most recently, Emulex announced the first implementation of data integrity features that came out of the Data Integrity Initiative, a joint initiative initially involving Emulex, LSI, Oracle, and Seagate. The Data Integrity Initiative defines methods for achieving end-to-end (application to disk drive) data integrity via checking mechanisms designed to prevent data corruption from occurring.

Archrival QLogic emphasizes the power efficiency of its 8Gbps HBAs, which do not include heat sinks or require cooling fans on the server, according to Satish Lakshmanan, director of marketing in QLogic’s host solutions group. For example, the company’s single-port QLE2560 adapter consumes 5.5W, and the dual-port QLE2562 consumes 6.2W.

In terms of performance per watt, QLogic claims 50,000 I/Os per second (IOPS) per watt on its single-port adapters and 63,000 IOPS per watt on its dual-port adapters using the company’s Dynamic Power Management technology. (Performance testing included a quad-core Intel Xeon server, Windows Server 2003 R2, and the IOmeter benchmark with 4KB read/write block sizes.)

QLogic also stresses performance in real-life applications such as MS-Exchange and Oracle databases. In Exchange tests using the IOmeter benchmark, QLogic’s 8Gbps QLE2560 topped 185,000 IOPS and 1,300MBps of throughput. (Full test configuration data and results for both MS-Exchange and Oracle testing are available at www.qlogic.com.)

Lakshmanan also points to ASIC-based hardware features that are optimized for virtual server environments, such as support for up to 256 NPIVs per port, and up to 256 queue pairs per port. For end users, the virtualization enhancements translate into benefits such as better utilization of I/O resources at the server level.

In the RAS (reliability, availability, serviceability) space, QLogic officials emphasize their adapters’ mean time between failure (MTBF)