With all the vendor chatter on FCoE at SNW last week, you’d think that it’s poised to become the final protocol for unifying storage and networking. What about iSCSI? Dell’s acquisition of EqualLogic demonstrates our belief that iSCSI is an integral part of the solution for unified fabric in the data center. So, does the emergence of FCoE change that? Not at all.
FCoE deserves respect as Ethernet’s successor to Fibre Channel (FC). FCoE acknowledges the dominant install base of Fibre Channel and also promises to consolidate LANs and SANs, which is especially valuable for blade server environments. With 10GbE FCoE, customers with 2 and 4 Gbps FC SANs can consolidate their network infrastructures and reduce the number of ports and cables that need managing. Their investment in FC management software and skills is also protected.
But FCoE needs to be put in perspective. Approximately ½ of the storage capacity shipped each year is still server-resident or external DAS and many SMBs (and enterprise departments) have yet to deploy SANs. For this wave of new SAN deployments, including many application-based deployments where customers already have some FC installed, iSCSI is better. This perspective is gaining traction and has been echoed in recent posts by Matt Baker and Dante Malagrino. Why?
· iSCSI is better for virtualization
· iSCSI is also better for Disaster Recovery because it is built on TCP, is routable and therefore enables less complex, easier to implement DR deployments.
· FCoE requires new, unique equipment, iSCSI does not:
· iSCSI runs over any industry standard Ethernet switches. FCoE will require 1) 10GbE DCE-capable switches between the host storage and 2) the addition of an FCoE bridge (or switch with integrated FCoE bridge).
· iSCSI runs on standard Ethernet adapters. For Windows, FCoE will require customers to buy a 10GbE Converged Network Adapter (CNA) for FCoE and LAN traffic. CNAs are forecast to be higher cost than standard 10Gbps Ethernet Adapters/LOMs and even 10Gbps iSCSI HBAs. I’ll save the discussion about the performance impacts of 10Gbps iSCSI (HBAs, TOEs, SW) vs. FCoE for a later date.
· Since network bandwidth is rarely the performance bottleneck in storage networks iSCSI can run on less expensive 1 GbE, while FCoE only runs on 10GbE. For many deployments, this forces customers to pay for bandwidth they don’t need.
· And finally, FCoE is built on two new and untested technologies (DCE and FCoE). It will take years of testing and qualification to build ultimate acceptance. Storage customers have demonstrated themselves to be among the most conservative in the IT community.
I agree with the FCoE proponents that maintaining separate networks for storage and networking is complex and inefficient. FCoE is commendable for providing the installed base of FC with an answer to cable sprawl and dedicated infrastructure. But the fact remains; the only technology that allows you to (affordably) unify your storage and network today is iSCSI. The only technology that provides compelling functionality benefits for DR and Virtualization is iSCSI. If you’re deploying a SAN for the first time or even if you are a Fibre Channel shop interested in the network consolidation and cost benefits of FCoE, why wait?
