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Storage Networking Times

Issue 7, January 2008
   

Education: The Business Benefits of Fibre Channel over Ethernet (FCoE) for Server I/O Consolidation.
Gilles Chekroun, Technical Chair, SNIA Europe BeNeLux Committee, beneluxtc-chair@snia.org

Data Center I/O consolidation is quickly becoming a reality and the adoption of 10 Gigabit Ethernet is helping the server administrators to implement I/O convergence.

The 10 Gigabit Ethernet network connectivity is driven by the rapid evolution of server hardware with quad core multi socket CPUs and by the growth of server Virtualisation software implementation allowing multiple Virtual Machines to run over the same hardware.

In turn, theses Virtual machines are driving the need for more access to storage and for more I/O bandwidth.



FCoE in the Server

Fibre Channel over Ethernet (FCoE) is a technology that transports Fibre Channel protocol over a lossless Ethernet network. This technology allows Data Center servers to natively connect to Fibre Channel SANs thus protecting investments in storage equipment, management and administration.

The ability of FCoE to integrate seamlessly in the Data Center allows an evolutionary approach to server administrators. The transport of IP and Fibre Channel over a single 10 Gigabit Ethernet cabling infrastructure reduces the number of server NICs and simplifies network topology with less need for power and cooling.

The business benefits are among others:

  • Fewer interface cards per server, therefore smaller servers (1RU) and so fewer cables
  • Power and cooling reduction
  • One set of access FCoE switches with LAN and SAN connectivity
  • Better performance with 10 Gigabit Ethernet connections
  • Seamless integration with existing Fibre Channel infrastructure and management

Simplifying Network Topology

FCoE simplifies the Data Centre network topology by reducing the number of server interfaces. Mission critical applications drive the need for multiple NIC and HBA interfaces on the server to create a redundant access to LAN and SAN switches.

This number of adapters per server also drives the need to have large servers (3 or 4 U) and so reduce the number of servers per rack.


Figure 1: With 4 or 5 adapters per server, administrators are forced to use 3 or 4 U machines and 2 x 2 kind of Top of the Rack switches – LAN and SAN.

When FCoE access switches are used, a single pair of adapters and a single pair of cables are needed to connect every server to both Ethernet and Fibre Channel networks.


Figure 2: With one or 2 FCoE adapters per servers, Administrators can use 1 U server and simplify network topology

Fewer Interfaces, Fewer Cables, Less Power, Less Cooling . . . And Greater Performance

FCoE technology is 10 Gigabit Ethernet-based and can run over copper cable like the new kind of twinax cable with SFP+ ends. IT managers can now fully realize the I/O consolidation and give every server access to centrally managed storage without having to invest in additional HBA adapters.

Inside this 10 Gigabit Ethernet pipe, administrators can use up to 8 Virtual Lanes, based on the User Priority in the VLAN 802.1q header, with VLANs for security, QoS and 802.1p Priority Flow Control (PFC) to provide the lossless Ethernet needed for FCoE.

The ability to transport Fibre Channel and IP over the same cable reduces the number of cables in the rack by a factor of two and having fewer adapters means consuming less power.

Integration in Existing Environments

FCoE doesn’t replace Fibre Channel but allows extension of native Fibre Channel networks up to the servers with 10 Gigabit Ethernet transport. FCoE switches in the top of the rack allow aggregation of 10 Gigabit Ethernet connections from the servers and split them to classical Ethernet LAN and Fibre Channel SAN thus preserving existing investments that have been made in the company.

Why 10 Gigabit Ethernet?

With the rapid growth in CPU technology and in particular, the multi-socket, multi-core CPUs, servers are becoming very powerful machines.

Next to this, there is a big Data Centre trend in server virtualisation so we see multiple virtual machines running in each server. All these machines want to access storage as well and 10 Gigabit Ethernet is the underlying technology to enable I/O convergence and multiple I/O streams on the same cable.

In the Ethernet world, there is nothing between 1 Gigabit Ethernet and 10 Gigabit Ethernet like we have on Fibre Channel 2-4-8 Gbps and 1 Gigabit Ethernet is definitely not enough theses days for the growth we see in server performance.

Unified Fabric

Until now, Data Centre networks were primarily two separate and very different networks: LAN and SAN. The first phase adoption of FCoE technology by server administrators will allow a unified fabric in the Data Centre server racks with lower costs and higher performance while reducing power consumption and enabling seamless integration with existing LAN and SAN networks.

The second phase will be adoption of FCoE by storage vendors and the ability to provide 10 Gigabit Ethernet FCoE connections to storage arrays. This may already happen during the second part of 2008, since some demonstrations have already been made at SNW US and more recently at SNW Europe 2007.

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