Rich Kenny | May 3, 2024

One of the most crucial measurements for a data centre is the efficiency of the IT equipment within the facility. The European Code of Conduct requires this to be reported as a metric called ITEEsv and this is the measurement agreed by the new Energy Efficiency Directive (EED).

What is ITEEsv?

IT equipment installed in a data centre consists of servers, storage systems, and network equipment. Due to the incompatibility of transferable benchmarks ITEEsv defines the method to obtain average energy effectiveness or efficiency for servers. It is specific to servers both because they are the highest energy users in the IT stack and also because it is possible to use a comparable benchmark to assess performance.

ITEEsv reflects the energy effectiveness and capability of the servers in the facility. It is a combination of:

• The capacity to do work per unit energy (capability)


• The amount of time the server is actually doing work (utilization)

The next bit looks a little bit complicated but only because it uses some formula which can be unfamiliar for some. I promise it isn't too bad!

How is ITEEsv Calculated

ITEEsv is determined and described by the below Formula:

 

The SMPE value is the maximum, or peak performance of a server, and is obtained from specifically approved performance benchmark results. The unit of SMPE depends on a benchmark method applied. In our case we use ITEEsv(SERT) with the unit of measurement being maximum Server side JavaScript Operations (SSJ_ops).

SMPOi is maximum power consumption of a server "i" in kW.

Basically it means that you add up all the performance of all the individual server configurations and divide it by all the power they use at maximum. This will then give you an average performance per unit of power for the estate.

What benchmarks can be used?

The maximum value of server energy effectiveness varies among CPU architectures and workloads but is often achieved at high CPU load levels. However only a few benchmarks, such as SERT and SPECpower, can find the approximate maximum server energy effectiveness. Most of the approved benchmark methods reveal the maximum performance (SMPE) and the maximum power consumption (SMPO) of a server.

ITEEsv is calculated as maximum performance divided by maximum power consumption and is recorded as the average of the energy effectiveness of all servers or a group of servers in a data centre. A higher ITEEsv value indicates higher processing capacity per unit of electric power and ITEEsv can be improved by utilising servers with higher energy effectiveness.

For the ITEEsv calculation a single approved benchmark method has to be applied for all servers and benchmark methods cannot be mixed. If SMPE and SMPO cannot be accurately determined for any particular servers in a group, those servers aren't included in the calculation of ITEEsv. When comparing historical ITEEsv values of a given data centre the same benchmark method has to be used every time ITEEsv is measured. You cant mix benchmarks and change them over time.

Why is it useful?

ITEEsv assists stakeholders with improving the energy effectiveness of their servers by providing a measure of work performed per unit of power consumed. When a server is replaced, the ITEEsv of the new equipment should be greater than that of the old equipment in order to improve the average score. 

When additional servers are added to increase capacity, the impact of the new equipment on ITEEsv should be determined. Likewise, when a data centre is reconfigured, the design ITEEsv should be an improvement over the baseline calculation.

What does ITEEsv reporting look like?

There are several approved benchmark measures of ITEEsv with several determination methods for SMPE.

• SERT - ITEEsv(SERT)


• SPECpower_ssj2008  - ITEEsv(SPECpower_ssj2008)


• LINPACK - ITEEsv(LINPACK)

For our reports we include the following information:

• ITEEsv value – SSJ_ops / Per Watt


• Benchmark chosen - SERT - ITEEsv(SERT)


• In case the measurement was made in part of the data centre, the measured server group or system where the ITEEsv calculation is applied