Redundancy is a critical issue for data centers because it typically translates into higher availability of the software services, where it's needed. In the past, the focus was on the need for redundant power and cooling systems for the entire data center. However, not all software needs to meet the same availability requirements. In addition, many of the software applications are rapidly changing to where they may need more or less availability. High availability (amount of time online) is often the ultimate objective, which is partially achieved through redundancy strategies.