Traditionally, when a server suffered a catastrophic failure, the sites it hosted went down and stayed down until it could be repaired or replaced. On a long enough timeframe, servers will fail — components don’t last forever, particularly those with moving parts like hard drives, but also electronic components. It was once an accepted feature of web hosting, some downtime was expected.
It’s almost impossible to guarantee zero downtime, even on the most advanced cloud platform, but modern cloud technology allows us to implement systems that make it an extremely rare occurrence.
To be considered a High Availability system, a cloud platform has to have a couple of features which are closely related to each other: the absence of single point of failure and failover in the case of a server going down. Read more