1.2 Floor Usage

What is it?

Floor usage is defined as:

Floor usage = (number of racks x rack floor usage x average rack utilization) / total floor area

where

number of racks = the total number of racks on the data center floor

rack floor usage = estimated floor usage of a single rack, including service area

average rack utilization = average percentage of rack space in use

total floor area = total amount of m2 available for racks

Here is an example. The data center floor of 500m² has 200 racks installed. Each rack of 60cm x 100cm and the required service in front of and behind the rack occupies 2m². On average each rack is 30% full. The floor usage is (200 x 2 x 30%) / 500 = 0,24 which is 24 when a scale from 0 to 100 is used.

Why should you care?

Floor usage reflects the balance between the various electrical and mechanical (E&M) elements that make up the data center as well as the correctness of capacity projections from the IT side. For available rack space we take the number of racks that can be placed on currently active floor space. Defining available rack space in this way rewards modular building techniques in which the actively cooled area can be increased and decreased according to demand.

How does it relate to the other items in the model?

Data center efficiency is influenced by floor usage because most of the E&M runs better at high utilization rates. Actual physical size also has its effect through fan power needed for air movement and increased electrical loss due to increased cable length. Floor usage is a delicate KPI, the target value is specific for each environment as it also determines the growth capacity of the datacenter. Typically, floor usage can be high when the data center is modular and the capacity can be tuned to the demand for resources.

Which KPI’s are directly related to this KPI?

• KPI’s Bypass and Recirculation measure the quality of the airflows and temperatures. Every level of floor usage requires its own plan for airflow management.
• KPI Change and Configuration Management influences this KPI because any change made to the data center and IT might impact the floor usage.
• KPI Product Lifecyle Management can impact the KPI when new hardware is added or existing hardware is (not) removed.
• KPI Capacity Management is used to plan the floor capacity.
• KPI Service Level Management supports chargeback and other means to run a data center successfully.