Three important attributes of any, good, Data Center Design are scalability, flexibility & high availability:

Scalability:
The Data Center Design must support fast and seamless growth without major disruptions.

Flexibility:
The Data Center Design must support new services without a major overhaul of its infrastructure.

High availability:
The Data Center Design must minimize single point of failure & offer predictable uptime by incorporating concurrent maintainability and fault-tolerance against hard failures. (A hard failure is a failure in which the component must be replaced to return to an operational steady state.)

Data Center scalability translates into the capability to sustain rapid growth in performance, the number of devices hosted in the Data Center / Computer Room & the quality of the services offered. Higher performance implies tolerance to very short-term changes in traffic patterns without packet loss and longer-term plans mapping growth trends to the capacity of the Data Center / Computer Room.

Data center flexibility translates into designs that accommodate new service offerings without requiring the complete redesign of the IT & support infrastructure architecture or drastic changes outside the normal periods scheduled for maintenance. The approach to flexibility is a modular design in which the characteristics of the modules are known, & the steps to add more modules are simple.