NETWORK MANAGEMENT
Challenges for data centre managers Keeping the efficient, efficient By Mike Heumann, Senior VP, Worldwide Sales and Marketing, NextIO
Virtualisation has been firmly positioned as a key business technology; a recent poll of IT managers for PC World revealed that over a third are already using server virtualisation. However, as managers try to realise efficiencies by adding more virtual machines and maximising their existing environment, they are faced with a Catch 22 situation. Virtualising means fewer physical servers, but increased efficiencies equate to more cables in order to deal with the increased levels of input/output.
Mike Heumann considers where the surge in server virtualisation leaves data centre managers.
Drawbacks In spite of the notable advantages that server virtualisation presents, its growth and development have revealed fault lines that will impede the technology’s future progression if left unaddressed. In March 2011, Gartner noted that
“most organisations will be well-served by focusing attention on the challenges within the server rack.” Hardware consumption is undoubtedly a major challenge to the expansion of server virtualisation. The server virtualisation market-leader, VMware, which currently boasts around 84 percent market dominance, has two solutions for
the increased levels of I/O experienced by servers that are working to capacity for the full time. The first involves traffic segmentation using a series of 1Gb Ethernet links. This allows the server to physically keep traffic flows separate and prioritise as appropriate. However, it drives up port, cable and switch count and costs while limiting the total number of applications that can economically deploy VMware. It also by its very nature increases the complexity of server management. The alternative option offered by
VMware is to use heavy duty full 10Gb links alongside its traffic QoS feature. While this method does reduce the cable count (by now your server is resembling Medusa’s head!) it can prove expensive as no DCM wants to be deploying 10Gb connections that will knowingly be underutilised. The other issue with this method is that physical separation no longer exists in the server environment and multiple traffic flows are now pushed down the same pipe, causing increased management complexities in a process that would normally be segmented. So while infrastructure virtualisation is a 21st century necessity as no business
is content to waste up to 75 percent in terms of server utilisation, its very nature causes associated I/O problems. The question becomes how do you optimise the optimised? The answer lies in how the subsequent data is handled. While VMware offer two solutions, both involve increased cabling and increased costs linked to capital and operational expenditure. This was never the goal of virtualisation, so it’s only right that the same principles VMware started with are applied to the resulting traffic.
The Solution There are two major strains of thinking in terms of I/O consolidation and where it should take place, either at the access or the network layer. The access layer sees I/O consolidation take place between the server and the network, while network layer I/O consolidation takes place within the fabric. While various market forces have proposed network layer solutions that rely on Ethernet and FCoE to reduce network switches and adaptors, it’s a methodology that doesn’t support Infiniband, SAS, or other host adapters. That leaves the prudent future thinking
Virtualisation is firmly positioned as a key business technology. 38 NETCOMMS europe Volume II Issue 4 2012
www.netcommseurope.com
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