First there was Ethernet. Then, there was IP over Ethernet. Next came the mixed use of Ethernet, IP, and the SCSI command set (iSCSI) to simplify storage and to bring down the cost and complexity of storage. Today, iSCSI and Fibre Channel are fighting it out in all but the largest enterprises, and both have their pros and cons. Even though these are the two primary contenders in today's block-level shared storage market, there are some other alternatives. The line is continuing to blur between these solutions as new initiatives are brought to market. Let's take a look at some new developments in storage infrastructure solutions.
Faster Fibre Channel
Two Gbps and 4 Gbps Fibre Channel are very common in the marketplace, and manufacturers are just now beginning to demonstrate 8 Gbps Fibre Channel gear. There are also standards in the works for Fibre Channel running at 10 Gbps and 20 Gbps. This venerable technology continues to improve to meet the increasingly robust storage needs demanded by the enterprise. In some cases, Fibre Channel solutions on the market rival iSCSI solutions from a price perspective (i.e., Dell/EMC AX150) for simple solutions. However, faster Fibre Channel still has the same skill set hurdles to overcome. Just about every network administrator knows IP, but Fibre Channel skills are a different matter.
iSCSI over 10G Ethernet
iSCSI has become a technology that deserves short-list status... and at a gigabit per second, no less. Many iSCSI naysayers point to its slower interlink speed as a reason that it won't stack up to Fibre Channel. However, iSCSI solutions are now on the cusp of moving to 10 Gbps Ethernet, meaning that iSCSI's link speed could surpass even the fastest Fibre Channel solutions on the market. Of course, iSCSI still has IP's overhead and latency, so we'll see how well 10 Gbps Ethernet performs in real-world scenarios when compared to 8 Gbps Fibre Channel.
Further, 10 Gbps Ethernet gear is still extremely expensive, so, for the foreseeable future, 10 Gbps-based iSCSI solutions probably won't fit the budgets of many organizations considering iSCSI as a primary storage solution. All this said, interlink speed is not necessarily the primary driver for replacement storage infrastructure in the enterprise. Performance boosts are often achieved by adding more disk spindles to the infrastructure or by moving to faster disk drives (i.e., SATA to 15K RPM SAS or Fibre Channel).
Fibre channel-over-IP (FCIP)
Fibre Channel-over-IP (FCIP) is a method by which geographically distributed Fibre Channel-based SANs can be interconnected with one another. In short, FCIP is designed to extend the reach of Fibre Channel networks over wide distances.
Internet Fibre Channel Protocol (iFCP)
Internet Fibre Channel Protocol (iFCP) is an effort to bring an IP-based infrastructure to the Fibre Channel world. Much of the cost of Fibre Channel is necessary infrastructure, such as dedicated host bus adapters (HBAs) and switches. These components can, on a per-port basis, add thousands of dollars to connect a server to the storage infrastructure. In contrast, transmitting Fibre Channel commands over an IP network would drive down infrastructure costs in a major way, requiring only gigabit Ethernet connections, which are already found on most servers. Further, even high-density Gigabit Ethernet switches cost only a couple thousand dollars. The main drawback to this proposal is the limitation to 1 Gbps Ethernet; although 10 Gbps gear is available, it would negate some of the cost benefit. On the plus side, iFCP (even on 10 Gbps Ethernet) would open Fibre Channel solutions to administrators that have IP-based skill sets. iFCP was ratified by the Internet Engineering Task Force in late 2002/early 2003.
ATA-over-Ethernet (AoE) hasn't enjoyed the popularity of iSCSI, but this isn't due to any technical hurdles. The AoE specification is completely open and only eight pages in length. AoE doesn't have the overhead of IP as does iSCSI since it runs right on top of Ethernet. Of course, this does limit AoE's use to single locations, generally, since raw Ethernet can't be routed. You can find more about AoE in one of my previous posts.
The future of storage is wide open. Between iSCSI, Fibre Channel ,and even AoE, solutions abound for organizations of any size and as the lines blur between some of these technologies, cost becomes less of an issue across the board.
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Since 1994, Scott Lowe has been providing technology solutions to a variety of organizations. After spending 10 years in multiple CIO roles, Scott is now an independent consultant, blogger, author, owner of The 1610 Group, and a Senior IT Executive with CampusWorks, Inc. Scott is available for consulting, writing, and speaking engagements and can be reached at firstname.lastname@example.org.