What method allows for the replacement of a cloud solution with minimal downtime, implementing updates gradually?

The method that allows for the replacement of a cloud solution with minimal downtime while implementing updates gradually is known as a rolling strategy. This approach involves updating a portion of the servers or instances in a deployment sequentially, rather than taking the entire service offline or updating all instances at once.

In a rolling strategy, the updates are rolled out to a set of servers, monitored for stability and performance, and once confirmed as stable, the update is rolled out to the next set. This allows users to continue accessing the service throughout the update process, which helps to minimize downtime and maintain a seamless experience. The gradual nature of the rolling strategy provides the opportunity to catch any potential issues without impacting the entire application, making it a highly effective method for cloud updates.

Other strategies, such as blue-green deployments, also minimize downtime but do so by maintaining two identical environments (blue and green) and switching traffic between them, rather than updating the application in sequence. Incremental deployment typically focuses on introducing smaller changes rather than systematic updates across instances, and migration strategies imply more extensive changes in infrastructure rather than simple updates.