Businesses want to choose reliable equipments, components and technologies while designing a network. You may deploy most reliable equipments from your trusted vendor or deploy most mature technologies with carefully do not forget eventually every system fails !
Depends on where is your datacenter located, different disasters may happen. For U.S storm, tornado is not uncommon. I remember just couple years before because of major flooding, Vodafone couldn’t serve to their customer in Turkey for at least 1 day.
Thus, resiliency is an important aspect of the design plan.Resiliency means, how fast you can react to failure with the simplest explanation.
Disaster recovery is the response and remediation that a company follows after a planned or unplanned failure. Businesses often have a secondary datacenter used mostly for backup. If the company has multiple datacenter, they can be used as active/active though.
Secondary datacenter can take the responsibility in the case of a primary datacenter fails if it is used as backup.
Recovery time will depend on business requirements.For the mission critical applications, business may tolerate very short if not zero down time. Then the cost of the required equipments in primary and backup datacenters, skilled engineer who can manage that design, complexity of the design changes based on the expectation of business from the disaster recovery service.
The amount of data loss a company can tolerate, also known as its recovery point objective (RPO) is a very important parameter. Recovery time can be between 2 hours to days or even weeks, based on the company’s applications. Highly critical applications require less downtime and less data loss. For that reason, a disaster avoidance solution might be a better option for businesses with many highly critical applications.