How clouds and fibre has remade the data centre
The data centre has become one big internal cloud
By Robin Layland | Network World US | Published: 17:04, 18 September 2009
A major transformation is sweeping over data centre switching. Over the next few years the old switching equipment needs to be replaced with faster and more flexible switches.
Three factors are driving the transformation: server virtualisation, direct connection of Fibre Channel storage to the IP switching and enterprise cloud computing.
They all need speed and higher throughput to succeed but unlike the past it will take more than just a faster interface. This time speed needs to be coupled with lower latency, abandoning spanning tree and supporting new storage protocols.Without these changes, the dream of a more flexible and lower cost data centre will remain just a dream. Networking in the data centre must evolve to a unified switching fabric.
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Times are hard, money is tight; can a new unified-fabric really be justified? The answer is yes. The cost savings from supporting server virtualisation along with merging the separate IP and storage networks is just too great. Supporting these changes is impossible without the next evolution in switching. The good news is that the switching transformation will take years, not months, so there is still time to plan for the change.
The story of how server virtualisation can save money is well known. Running a single application on a server commonly results in utilisation in the 10% to 30% range. Virtualisation allows multiple applications to run on the server within their own image, allowing utilisation to climb into the 70% to 90% range.
This cuts the number of physical servers required; saves on power and cooling and increases operational flexibility.
The storage story is not as well known, but the savings are as compelling as the virtualisation story. Storage has been moving to IP for years, with a significant amount of storage already attached via NAS or iSCSI devices. The cost saving and flexibility gain is well known.
The move now is to directly connect Fibre Channel storage to the IP switches, eliminating the separate Fibre Channel storage-area network. Moving Fibre Channel to the IP infrastructure is a cost saver.
The primary way is by reducing the number of adapters on a server. Currently servers need an Ethernet adapter for IP traffic and a separate storage adapter for the Fibre Channel traffic. Guaranteeing high availability means that each adapters needs to be duplicated resulting in four adapters per server.
A unified fabric reduces the number to two since the IP and Fibre Channel or iSCSI traffic share the same adapter. The savings grow since halving the number of adapters reduces the number of switch ports and the amount of cabling. It also reduces operational costs since there is only one network to maintain.