In the data center industry, equipment redundancy is widely utilized to achieve high system availability, often required to be in the range of 99.999% (five nines). However, the required level of redundancy is dependent on equipment reliability.
For instance, an N+1 system cannot achieve high levels of availability with unreliable system components that have too high of a probability for simultaneous failure. Reliability affects availability, but they are not the same thing in a world that experiences downtime and failures. Reliability also impacts operating costs. More downtime equals more maintenance and repair spending.