OEMs need flexibility, upgradeability when integrating Fibre Channel support: understand the tradeoffs, know the options

Computer Technology Review, April, 2004 by Joe Teolis

With demands for networked storage growing, the choice for OEMs isn't whether to incorporate Fibre Channel storage connectivity in servers, but in what form to provide that support. The choices range from very tight integration on the server or storage system motherboard, to quasi-custom integration through "mezzanine" boards for a blade server (or other custom applications), to the most flexible option of providing expansion slots for Host Bus Adapters (HBAs).

OEMs should choose different options for different customer sets at different points during the adoption curve of any given I/O (input-output) standard such as Fibre Channel. Among the variables to consider is the adoption rate of the I/O technology, how quickly that technology is changing, and how much flexibility the customer needs in changing or upgrading their storage interconnect.

Regardless of the form factor, OEMs should choose the I/O technology from a vendor who offers the greatest flexibility for OEMs and customers, the greatest ease in upgrading their technology, the largest installed base and the highest brand awareness in the marketplace.

The Fibre Channel Challenge

Organizations of all sizes need to constantly store more data due to an increased reliance on information systems, the data generated by 24x7 e-commerce, as well as new regulations that require organizations to keep more data for longer periods of time.

The form factor question has become all the more compelling as a new class of cost-conscious FC users emerges, namely small and medium business (SMBs). These users currently employ DAS and face issues very similar to those that first led enterprises to turn to networked storage. This new market segment for Fibre Channel broadens the discussion to the low-cost volume server market.

In the past, customers might have met these needs by adding more direct-attached storage to individual servers. However, as the number of servers grows, this becomes increasingly hard to manage and inefficient because customers might be forced to add new disk hardware to one over-taxed server while storage sits nearly empty on a nearby, underused server.

Fibre Channel has been the protocol of choice for high-end storage needs because of its high throughput, reliability, scalability and the maturity of the applications used to manage and administer it. FC offers three times the throughput of SCSI (Small Computer System Interface), improving overall data throughput and reducing the "backup windows" during which applications must be taken off-line to allow data to be backed up. Fibre Channel also allows servers to be connected to storage devices over distances of as much as six miles, making it easier to perform remote data backups to provide business continuance in the event of a disaster at the main data center.

For many years, large enterprises have used FC storage-area networks (SANs) to aggregate their storage. By allowing servers to share a single pool of networked storage, they allow the more efficient use of all available storage, improve the availability of data, and reduce network congestion by removing backup traffic from the corporate data network.

More and more organizations in the SMB markets are also looking at SANs built around lower-cost disk drives. While these arrays may not offer the same levels of scalability, throughput and reliability as Fibre Channel technology, they meet the requirements of many SMB customers and are an increasingly cost-effective alternative to direct-attached storage. Finally, the increasing processing power of even industry-standard, Windows-based servers makes them able to run applications, which require the block-level data access provided by Fibre Channel.

However, different customers might need different forms of FC support depending on their price sensitivity, the amount of physical space available for their servers, and how often they'll need to upgrade their infrastructure. OEMs don't want to ship server hardware with more I/O capabilities (and thus more cost) than a customer is willing to pay for, or to ship I/O capabilities that won't work for more than a year or two due to rapidly evolving storage standards. OEMs can, however, capture market share by shipping the right Fibre Channel support in the right form factor to the right customers for the targeted market.

To understand the trade-offs, it's important to understand what constitutes Fibre Channel support. The first requirement is a physical FC connection, which supports different types of cable (optical as well as copper) as well as the different types of Fibre Channel connections. The two key connection methods are loop mode, which allows as many as 126 devices to share the connection directly in a loop, or a switched fabric that allows thousands of devices to share exclusive point-to-point connections.

Fibre Channel also requires hardware and software to support the proper formatting of data packets and other functions such as controlling the flow of the packets, correcting any errors in transmission, and (in the case of TCP/IP) reassembling packets in the proper order when they arrive at the server.