16 Gbps Fibre Channel – Do the Benefits Outweigh the Cost?

With today’s technology there can be no status quo.  As the IT industry advances, so must each organization’s efforts to embrace new equipment, applications, and approaches.  Without an ongoing process of improvement, IT infrastructures progressively become outdated and the business group they support grows incrementally less effective.

In September of 2010, the INCITS T11.2 Committee ratified the standard for 16Gbps Fibre Channel, ushering in the next generation of SAN fabric.  Unlike Ethernet, Fibre Channel is designed for one specific purpose – low overhead transmission of block data.  While this capability may be less important for smaller requirements where convenience and simplicity are paramount, it is critical for larger datacenters where massive storage repositories must be managed, migrated, and protected.  For this environment, 16Gbps offers more than twice the bandwidth of the current 8Gbps SAN and 40% more bandwidth than the recently released 10Gbps Ethernet with FCoE (Fibre Channel over Ethernet).

But is an investment in 16Gbps Fibre Channel justified?  If a company has reached a point where SAN fabric is approaching saturation or SAN equipment is approaching retirement, then definitely yes!  Here is how 16Gbps stacks up against both slower fibre channel implementations and with 10Gbps Ethernet.

Emulex
Model
Port Speed Protocol Average HBA/NIC   Price Transfer
Rate
Transfer Time for 1TB Bandwidth
Cost per
MB/sec.
Bandwidth
Difference
LPE16002 16 Gbps Fibre Channel $1,808 1939 MB/sec. 1.43 Hrs. $0.93 160%
OCe11102 10 Gbps Ethernet $1,522 1212 MB/sec. 2.29 Hrs. $1.26 100%
LPe12002 8 Gbps Fibre Channel $1,223 800 MB/sec. 3.47 Hrs. $1.53 65%
LPe11000 4 Gbps Fibre Channel $891 400 MB/sec. 6.94 Hrs. $2.23 32%

This table highlights several differences between 4/8/16 Gbps fibre channel and 10Gbps Ethernet with FCoE technology (sometimes marketed as Unified Storage).  The street prices for a popular I/O Controller manufacturer clearly indicates there are relatively small differences between controller prices, particularly for the faster controllers.  Although the 16Gbps HBA is 40% quicker, it is only 17% more expensive!

However, a far more important issue is that 16Gbps fibre channel is backward compatible with existing 4/8 Gbps SAN equipment.  This allows segments of the SAN to be gradually upgraded to leading-edge technology without having to suffer the financial impact of legacy equipment rip-and-replace approaches.

In addition to providing a robust, purpose-built infrastructure for migrating large blocks of data, it also offers lower power consumption per port, a simplified cabling infrastructure, and the ability to “trunk” (combine) channel bandwidth up to 128Gbps!   It doubles the number of ports and available bandwidth in the same 4U rack space for edge switches, providing the potential for a saving of over $3300 per edge switch.

Even more significant is that 16Gbps provides the additional performance necessary to support the next generation of storage, which will be based on 6Gbps and 12Gbps SAS disk drives.  Unlike legacy FC storage, which was based upon 4Gbps FC-AL arbitrated loops, the new SAS arrays are on switched connections.  Switching provides a point-to-point connection for each disk drive, ensuring every 6Gbps SAS connection (or in the near future, 12Gbps SAS connection) will have a direct connection to the SAN fabric.  This eliminates backend saturation of legacy array FC-AL shared busses, and will place far greater demand for storage channel performance on the SAN fabric.

So do the benefits of 16Gbps fibre channel outweigh its modest price premium?  Like many things in life – it depends!  Block-based 16Gbps fibre channel SAN fabric is not for every storage requirement, but neither is file-based 10Gbps FCoE or iSCSI. If it is a departmental storage requirement or an environment where NAS or iSCSI has previously been deployed, then replacing the incumbent protocol with 16Gbps fibre channel may or may not have merit.  However, large SAN storage array are particularly dependent on high performance equipment specifically designed for efficient data transfers.  This is an arena where the capabilities and attributes of 16Gbps fibre channel will shine.

In any case, the best protection against making a poor choice is to thoroughly research the strengths and weaknesses of each technology and seek out professional guidance from a vendor-neutral storage expert with a Subject Matter Expert level understanding of the storage industry and its technology.

About Big Data Challenges

Mr. Randy Cochran is a Senior Storage Architect at Data Center Enhancements Inc.. He has over 42-years of experience as an IT professional, with specific expertise in large and complex SAN/NAS/DAS storage architectures. He is recoginzed as a Subject Matter Expert in the enterprise storage field. For the past five years his primary focus has been on addressing the operational requirements and challenges presented by petabyte-level storage.

Posted on June 5, 2012, in Topology, Uncategorized and tagged , , , , , , , , , , , , , . Bookmark the permalink. Leave a comment.

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