The iSCSI vs. Fibre Channel SAN debate remains unresolved after almost a decade. ISCSI provides cheap, fast storage networks that can rival Fibre Channel SAN storage at a fraction of the cost. With the steady march of faster Ethernet and tight integration of virtual server systems, it's time to stop arguing about IOPs and rarified algorithms and think more strategically on how to utilize iSCSI storage.
Any solid return on investment evaluation looks beyond just raw input/output numbers to determine the benefit of an enterprise's IT products. There are four features to keep in mind when considering the value of today's Gigabit Ethernet (GbE) networks when used with critical applications.
- Scalability. Servers moving from local-attached disks can now attach to GbE iSCSI (1 gig bandwidth) connections, then quickly double bandwidth from one to two ports on a GigE switch and increase again to four total ports. The host systems don't require any client-side infrastructure changes, additional SAN cards, proprietary cables or unique switches. It scales without major investment beyond building out relatively cheap GigE switches. This puts iSCSI storage on the same level of cost savings provided by a general virtualization strategy.
- Compatibility. In the past, proprietary infrastructure was the only trusted method for seamless connection between storage and server environments, with the same vendor supporting the entire storage network. That was great if you could afford it, because it eliminated most compatibility issues. But today there are solid standards across iSCSI vendor lines, with the latest step forward being Microsoft iSCSI Software Initiator for Windows Server 2008, which simplifies implementation regardless of the hardware adapters used. This means a greater number of vendors to choose from and it opens the door to competitive hardware pricing and innovation.
- Native features. A set of fully tested features, such as multipath I/O, multiple connections and remote boot, is now available for iSCSI management. 10 GbE is a strong contender with these tools, and it can be the cost-effective way to spin up long-delayed consolidation projects.
- Hyper-V. Windows Server 2008 R2 Hyper-V is a big leap forward. Today's Hyper-V allows iSCSI guest initiators to connect directly to the SAN, providing a virtual 1-to-1 path from applications to storage. Some options can create networking overhead, but based on need, that can be a small price to pay when the result is a more efficient and dynamic data center. As an added bonus, smoothing the P2V migration, the powerful Hyper-V Virtual Machine Queue closes the performance delta from physical to virtual servers.
One caveat noted by some advisors: When using technologies like data center bridging and Fibre Channel over Ethernet (FCoE), there can be perceived bottlenecks in iSCSI. But that assumes a hard right, away from existing SAN to iSCSI, with no transitions. However, as described, 10 GbE scales and can handle converged traffic over high-capacity SAN. As for the iSCSI vs. FCoE debate, that's really a design decision. If you are expanding an existing Fibre Channel SAN, consider FCoE.
However, as an integrated solution, 10 GbE iSCSI is enterprise-ready.
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