By Kevin Komiega
—It has been several years since storage networking vendors began their push for putting advanced data services and storage management functions on fabric switches. So-called "intelligent switches" have since emerged with the ability to facilitate storage virtualization, provisioning, and certain levels of data migration and management. However, end-user adoption of fabric-based applications and intelligent switches has been nominal. To partially address this situation, the industry is in the process of developing a standard aimed specifically at helping smart switches live up to their potential.
The common definition of an intelligent switch, at least according to the biggest vendors selling these devices, is a network device with switching at its core that can process Fibre Channel frames at wire speeds while performing additional data services. But adding heterogeneous migration, replication, virtualization, and other functions to switches is not a simple task. That's why the industry is currently developing the Fabric Application Interface Specification (FAIS) to define a common application programming interface (API) framework for the implementation of fabric-based storage applications. It's an effort that the industry hopes will ultimately bring the promise of intelligent switches to fruition by making it easier for hardware and software vendors to run their applications on network devices.
According to the T11 Technical Committee, which is the group within the InterNational Committee for Information Technology Standards (INCITS) responsible for device level interfaces, the initial FAIS specification provides for a handful of fabric-based functions, including the identification and initialization of real and virtual storage resources, the establishment of parameters and mappings that control SCSI operations, the execution of supporting SCSI commands on behalf of a virtual storage devices, and the execution of data distribution, replication, and journaling functions appropriate to storage applications.
The first crack at the FAIS standard, according to Bill Terrell, senior director of marketing in QLogic's Storage Solutions Group, has some obvious holes. "As with all emerging, complex technologies, the first shot over the bow might not be the right one," says Terrell. "The question is whether FAIS has been cut at the right level in the stack."
Terrell says the current version of FAIS is not complete enough to allow hardware and software vendors to provide complete solutions for intelligent switches, although the main components of the standard are in place. "There are still some missing pieces, and everyone knows that, but we are pushing forward with the core pieces that we all agree on and will push forward with other features as time progresses," he says.
"In an ideal world we believe the network is the best place to perform advanced data services because it provides a layer of independence from proprietary hardware. From that perspective, having data services in the network means that they can run against any brand of storage array or server," says Terrell.
But, he says, the devil is in the details. "Today [the industry] does not have a complete enough solution for users to feel completely comfortable with the concept."
QLogic's version of a smart switch is the SANbox 8000 Series Storage Services Platform, which includes two models—the SANbox 8200 and 8202. The fabric-based platforms were built specifically to host applications in the network, such as virtualization, mirroring, and snapshots.
The T11 group is currently working on FAIS-2, the next revision of the specification, which will include a set of additional functions to the FAIS standard, such as enhanced separation of control and data paths, additional methods for routing exceptions from the data path to the control path, better methods for handling exceptions and asynchronous events in the control path, and enhanced methods for discovering and configuring data-path capabilities, according to the T11 Website.
FAIS-2 is slated for completion by next June.
Cisco has been a proponent of FAIS from the beginning and is one of the companies helping to develop the standard. Rajeev Bhardwaj, manager of product management in Cisco's Data Center and Storage Technology Group, says that interest in intelligent switches is growing as more and more users continue to consolidate their storage infrastructures.
"The broad trend we see in the data center is consolidation, with more and more applications residing on a common infrastructure," says Bhardwaj. "Cisco is delivering intelligent switches that enable virtualization and SAN extension for disaster recovery and business continuity with high port counts, scalability, and tiered connectivity for multi-protocol environments."
Cisco's fabric-based intelligence play is found in its MDS 9000 series of multi-layer SAN switches. Cisco's approach to moving applications into the fabric is based on the addition of the MDS 9000 Storage Services Module (SSM), a line card that fits into any modular MDS 9000 chassis and enables network-hosted storage applications such as provisioning, data migration, replication, and backup/recovery.
SSM cards operate in conjunction with Cisco's SAN-OS software and, according to the company, provide support for FAIS-based storage applications, appliance-based storage applications via the SANTap protocol, and network-accelerated serverless backup.
Like QLogic and Cisco, Brocade says FAIS is the answer to boosting end-user confidence and spurring adoption of fabric-based applications.
"Customers today are not really using the full capabilities of the products and there are a couple of reasons for that. For example, users might be holding off on adoption until a strong standard is in place," says Mario Blandini, director of product marketing at Brocade. "Changing behavior takes time and some users are hesitant to deploy full-blown data services in the fabric until the technology has really proven itself."
Brocade entered the intelligent switching market with its SilkWorm Multiprotocol Router, which is also known as the AP7420 intelligent switch. The router provides a platform for integrated storage services and acts as a foundation for SAN extension, advanced performance monitoring, and zoning capabilities.
John Webster, co-founder and senior analyst at the Data Mobility Group, has followed the progress of the FAIS standard since its inception four years ago. "FAIS was developed because vendors did not want to be writing to a bunch of different APIs. They wanted one standard implementation," says Webster. "Thereafter, there was a realization that it was going to be a lot harder than they originally thought it was going to be."
Intelligent switches are becoming more and more advanced and the FAIS standard will enable a variety of applications to run in the fabric, but the question remains: When?
"What we are seeing today is intelligent switches coming to market that offer a service or a combination of a few services that are marketed as killer applications. What we are not seeing is all of the applications in one box," says Webster. "Intelligent switches will eventually get off the ground, but the question right now is: Will they get off the ground too late?"
Webster also notes that there are a number of alternatives to intelligent switches that enable fabric-based applications today. One example is the network controller-based approach used by Hitachi Data Systems in its TagmaStore Network Storage Controller model NSC55. The NSC55 offers controller-based virtualization, logical partitioning, and universal replication.