QoS in a Data Center ?

Do we need to implement QoS in a Data Center ?

First of all we should describe what QoS is: Quality of Service (QoS) is a set of standards and mechanisms for ensuring performance of critical applications, by tagging the traffic with different labels according to the priority assigned to it. That means that we are ensuring the performace of some traffic but leaving another part as secondary. So in case of congestion of the net, we can loose some less prioritized packets.

As a data center manage a lot of different types of traffic, and need to ensure the availability and reliability of some services we should use QoS mechanism. What we will use tu implement quality of service in a data center is the IEEE standard, DCB.

DCB (Data Center Bridging), provides bandwith allocation to a specific type of traffic and enhances Ethernet transport reliability with the use of priority-based flow control (PFC).

In this cisco paper you can find much more information about DCB, its features and benefits.

Finally I would like to mention this interesting post that discuses the need of a QoS implementation in a data center by arguing  "bandwidth is cheaper than QoS-induced complexity".