Hardware Today: Turning on SAN Switches
November 7, 2005
Storage-area network (SAN) switches are the heart of every SAN. Fibre Channel (FC) cables from the servers connect to switches and from there to disk arrays, thus enabling many servers to store data on one or more disk arrays.
The explosion in storage demand has made for a healthy SAN switch market as of late. According to DellOro Group, SAN switch revenue rose from just under $1 billion in 2002 to $1.1 billion in 2003 and almost $1.3 billion last year. Tam DellOro, an analyst at DellOro Group, sees this growth in demand as having multiple dimensions.
"Existing users on SANs are increasing the amount of backup they require and want to back up to multiple locations, says Dell'Oro. In addition, the number of users is rising due to legislation that holds them accountable for retaining certain information. Thats forcing them to contact the storage department to ask to be put on the storage network.
The undisputed SAN switch market leader is Brocade, which has 47.4 percent market share, followed by McData, with 28.6 percent share and Cisco (with 14.9 percent). Brocade believes the transition to 4 Gbit per seconnd FC switches is the big news in the storage world, and it offers a complete family of 4 Gbit per second switches from entry-level to enterprise SANs. The Brocade SilkWorm 200E SAN is a 4 Gb entry and departmental switch with eight to 16 ports. The Brocade SilkWorm 4100 was the industrys first 4 Gbit per second midrange SAN switch. It is available in configurations of 16, 24, and 32 ports. At the high-end, the Brocade SilkWorm 48000 is a 4 Gbit per second switch that supports up to 256 ports.
To maximize the benefits of server consolidation via blade servers, an increasing number of chassis have been equipped with integrated SAN switch modules, says Buiocchi.McData Directs
Although Brocade rules the broad market, McData leads at the high end. Known as SAN directors, the term Director applies only to the very largest SAN switches with the highest number of ports and the most robust failover features. McData claims a 44 percent share of director-level switches.
For the high-end market, the trend is toward more intelligence in the SAN fabric, says Tom Clark, director of solutions and technologies at McData. Auxiliary technologies, such as storage virtualization, are being deployed in the data center to enable more flexibility is managing storage resources, and reduction of day-to-day operational costs.
McData provides a 256 port-SAN director, the Intrepid 10000 series. This product line offers 99.999 perecent availability, 10 Gbps interswitch links, and the capability to subdivide the director into independent SAN partitions shared between multiple data center applications. The company also provides a 140-port director, the Intrepid 6140.
Clark is seeing the emergence of embedded SAN blade switches, along with products optimized for the midtier market, including inexpensively priced SANs that take advantage of iSCSI. McDatas Sphereon 4400 product line, for example, is a compact 4 Gbps switch that scales from eight to 16 ports.
Lower cost and simplicity of installation are making SANs a viable alternative for the midtier, says Clark. We are also seeing the integration of server platforms and SAN connectivity in the form of blade servers and blade SAN switches.
Building on its network switch success, Cisco has entered the storage switch market with a vengeance. From a 5.9 percent market share in 2003 to 14.9 percent last year, Cisco has recorded quarterly market share as high as 20 percent. Like its rivals, Cisco is talking up increased intelligence in the SAN fabric and lower costs.
The network is the ideal place for adding intelligence to enable certain applications, such as data migration, volume management, and backup acceleration, says Paul Dul, director product management at Ciscos data center and storage business unit. Multiprotocol SANs are now a reality with all major SAN switch vendors at the very least announcing plans to support transport protocols beyond Fibre Channel.
Cisco was the first vendor to make multiprotocol SANs available through a wide variety of interface modules and multiprotocol chassis options. The MDS 9020 Fabric Switch is a low-end offering with 4 Gbps performance on 20 ports, for an aggregate bandwidth of 160 Gbps.
In the midrange, the Cisco MDS 9216i Multilayer Fabric Switch integrates FC and IP into a single form factor. It provides 14 2-Gbps FC interfaces and two Gigabit Ethernet ports that can be configured to support either FC over IP (FCIP) for long distance SAN extension or iSCSI for cost-effective SAN expansion. In the director class, the Cisco MDS 9509 Multilayer Director supports 16 to 224 1/2-Gbps auto-sensing FC ports or eight to 48 1-Gbps Ethernet ports in a nine-slot modular chassis. That means up to 672 FC ports in a single rack.
Collectively, Brocade, McData, and Cisco account for more than 90 percent of the pie. Next in line come QLogic (4.5 percent), CNT (4.1 percent, and recently acquired by McData), Emulex (0.3 percent ) as well as startups, such as Troika Networks (just gobbled up by QLogic) and Maxxan, which are focusing on the red-hot intelligent switch space.
Maxxan believes that intelligence and integration of functions are among the key trends emerging at the switch level.
User surveys have shown that users have a clear preference for an integrated approach to storage network services that avoids the need to deploy a multitude of devices, says Greg Farris, senior product Manager at Maxxan.
He gives the example of storage security services. There is a clear need to encrypt sensitive stored data, but, he says, the options to this point have not been satisfactory. Users with larger data centers have had only the options of using software encryption that exacts a severe performance penalty or deploying a rack full of expensive appliances that do not provide adequate scalability. He believes most enterprises would prefer an integrated service in an intelligent switching platform that can scale in performance to meet their needs.
Another example is storage virtualization integration, says Farris. While some users have adopted external appliances, we believe more will be interested in evaluating a solution that integrates transparently with other services.
To meet these needs, the Maxxan MXV250 scales from 16 to 64 ports within a single, centrally managed chassis. It has the ability to function either as a SAN switch that supports storage applications or as a storage application platform to support applications, such as storage security, storage virtualization, snapshots, data replication, and NAS as network services. The Maxxan MXV500, on the other hand, is a higher-end model. It supports 16 to 256 ports, as well as 512 ports in a second chassis.
4 Gb Delays
Most of the vendors mentioned in this article have either announced or shipped 4 Gb technology. Tam DellOro warns, however, that there have be some company-specific glitches to these newer products, and relatively few have made it into a production environment.
SANs are often used to back up the crown jewels so these companies cant afford them going down, says DellOro.
As a result, 4 Gb gear generally undergoes rigorous testing from large systems integration firms before enterprises permit them to be deployed with mission-critical applications. Once a vendor proves its mettle in terms of reliability, redundancy, and resiliency, she foresees a rapid adoption curve.
Although users are cautious, I expect to see strong demand for 4 GB and strong demand for switches due to corporate demand and legislative pressure, says DellOro. But it will take another six to nine months to complete ongoing testing.