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Why choose Fibre Channel for virtualization storage networking?

Fibre Channel technology remains the quintessential approach to storage area networks (SANs) for virtualization storage

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networking, but its traditional leading role in SAN implementation is waning as newer SAN technologies take their place in the enterprise.

With current speeds to 10 Gbps, Fibre Channel is typically known for its overall performance and inherent security in storage networks. It’s a dedicated storage fabric, so virtualization storage traffic does not compete for bandwidth with user traffic as it would on an ordinary LAN. Connectivity between servers and virtualization storage also rarely extends to the LAN or WAN, so Fibre Channel benefits from a level of isolation that insulates the SAN against attack.

“Fibre Channel by itself being a unique storage protocol is relatively protected by its obscurity,” said Ray Lucchesi, president and founder of Silverton Consulting Inc. in Broomfield, Colo.

Cost has long been deemed a disadvantage for Fibre Channel storage networking, although experts are quick to point out that economic factors are changing.

“Sometimes I see Fibre Channel being cheaper than iSCSI,” said Greg Schulz, founder and senior analyst at StorageIO in Stillwater, Minn. “Sometimes I see iSCSI being more complex than Fibre Channel,” he said.

Schulz added that 10 GbE products are still new and can be exorbitantly expensive compared to well-defined and long established Fibre Channel storage networking products. Ultimately, Fibre Channel costs are greatest for new deployments that require a full complement of host bus adapters (HBAs), switches, cabling and other infrastructure. Expanding an existing Fibre Channel SAN is generally more affordable than shifting to other SAN types.

Still, the complexity of Fibre Channel technology remains an issue that any organization must weigh carefully. Fibre Channel is a separate network that’s radically different than Ethernet, so organizations that choose to deploy a Fibre Channel SAN for virtualization storage networking have to maintain two networks rather than just one. This adds to data center costs and requires additional IT staff that is knowledgeable about Fibre Channel technology.

As with cost, management and complexity concerns are not so significant if a Fibre Channel SAN is already in place, but it can be a huge obstacle when planning a Fibre Channel SAN from scratch.

Virtualization can add to the complexity and management woes of a SAN, and Schulz warns that the virtualization storage system should adequately support the hypervisor.  An increase in mixed virtualization environments means that the shared storage system may need to handle multiple hypervisors like VMware, Hyper-V or XenServer.

In addition, Schulz said that the virtualization storage system should support key features of the virtual environment, including live migration. Once you’ve identified a storage system that supports your virtual environment, it’s time to consider the management interface that should ideally provide administrators with a holistic view that includes storage, networks and servers. “Does the interface enable or get in the way?” Schulz said. “It should be transparent.”

In spite of its maturity, Fibre Channel storage networking technology provides a high-bandwidth, low-latency storage network that is well suited to handling aggregated storage traffic that is common when multiple virtual machines reside on hosts. Features like live migration are also well supported with this virtualization storage networking option.

“A virtual machine can have a virtual Fibre Channel HBA port that migrates with it for VMotion or Live Migration to another server,” Lucchesi said, “so its zoning and access to LUNs can migrate with it fairly easily.”

Considering the competitive cost point for 8 Gig Fibre Channel versus 10 GbE today, many experts expect Fibre Channel to remain a viable option for virtualization storage networking in data centers for years to come.

About the author
Stephen J. Bigelow
, a senior technology editor in the Data Center and Virtualization Media Group at TechTarget Inc., has more than 20 years of technical writing experience in the PC/technology industry. He holds a bachelor of science in electrical engineering, along with CompTIA A+, Network+, Security+ and Server+ certifications and has written hundreds of articles and more than 15 feature books on computer troubleshooting, including Bigelow’s PC Hardware Desk Reference and Bigelow’s PC Hardware Annoyances. Contact him at sbigelow@techtarget.com.

This was first published in May 2011

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