The Amazon Web Services or AWS public cloud system uses a concept called “availability zones” to offer client companies redundancy and failover for business systems. With availability zones, companies can ensure that the system will still keep working flawlessly, even if one particular data center is compromised.
Availability zones are a strategy for helping to handle things like natural disasters, malware attacks or other IT disruptors. They also illustrate the principle of failover – that when a central system’s operation location experiences a power blackout, or some other emergency, the system as a whole is not compromised, and its operations are not interrupted.
With availability zones, AWS launches multiple servers in different zones. Sometimes these zones are launched in different geographical regions, which raises issues of cost and latency. Companies may try to keep servers geographically closer to the resources they need. A greatly distributed system can slow things down a bit. There will also be use and storage charges related to the use of different availability zones, and especially availability zones in different regions. As with all kinds of cloud procurement choices, companies have to decide whether they need a backup in another availability zone, and whether that service will be extended to clusters of additional user nodes in the zone itself, or just provide backup services.
In general, availability zones provide an excellent example of the principle of redundancy. With just one server operation in a particular location, there is the distinct chance of failure and downtime. By multiplying into two availability zones, that chance becomes greatly reduced and practically eliminated. With the right kind of setup, the chances that both servers in different zones are compromised at the same time is extremely small.