Ethernet 10gigE takes on Fibre Channel
- — 02 May, 2007 08:31
BlueArc's latest and largest Titan 2500 NAS/iSCSI product now has 10 gigabit Ethernet support, signalling the arrival of serious Ethernet competition to Fibre Channel.
Fibre Channel connects storage area networks (SANs) to servers at 2Gbit/s with a current transition to 8Gbit/s. It provides a guaranteed delivery of data blocks and this, together with its speed has limited the incursion of IP SANs, ones using iSCSI signals sent over Ethernet.
When Ethernet runs at 1Gbit/s it has a speed disadvantage to Fibre Channel that negates its low cost and simpler operation. It's possible to aggregate these Ethernet links to increase bandwidth, but this complicates matters. It means multiple devices, aggregated multiple network switches, or putting up with throttled back applications.
This disparity remains when customers upgrade to a 10Gbit/s Ethernet infrastructure while their storage infrastructure has no 10gigE support.
With end-to-end 10gigE networking, from storage to server, then the full bandwidth is available and iSCSI block storage, together with networked-attached (NAS) file storage, can have a truer comparison with Fibre Channel.
Greg Schulz, a senior analyst at StorageIO, said: "10 Gigabit Ethernet (is) becoming table stakes for iSCSI and NAS connectivity."
EMC's Chuck Hollis, VP of technical alliances, said in his blog: "There's nothing wrong with FC SANs. They work as advertised. And as the saying goes, 'don't fix it if it ain't broke.'" FC delivers the data goods with no latency whereas iSCSI is unpredictable. Server apps can fail if storage access latency is too long.
However, increased Ethernet speed can help to sort that out. If cost and green pressures on IT increase then Ethernet economics could start swinging SAN access in Ethernet's favor in enterprises. Hollis said: "Servers that use on-board Ethernet use less energy than those that use an add-on FC card (or two!), besides being smaller (think very dense blade servers). (I) don't know if the discussion will progress to that level, but it's possible."
"Going out a bit farther, I believe that further cost reductions in 10Gbit/s Ethernet technology will encourage people to take another look at an alternative to FC. Once it starts becoming standard on server motherboards, and port costs come down to near where 1Gbit/s technology is today, the discussion will open up again."
The arrival of end-to-end 10Gbit/s Ethernet storage networking may well herald the opening up of this FC or Ethernet discussion.