What MongoDB mechanism addresses high availability?

Replication is the mechanism in MongoDB that ensures high availability. It involves creating multiple copies of the same data set across different servers, which allows the system to maintain operational continuity even in the event of a failure. With replication, if the primary server (the primary replica set member) goes down, one of the other members can automatically take its place as the new primary. This seamless transition helps to ensure that applications continue to have access to data without interruption. Additionally, replication enhances data durability and allows for load balancing of read operations across multiple servers.

In contrast, sharding is primarily concerned with distributing data across multiple servers to manage data growth and improve performance, but it does not inherently provide protection against server failures. Encryption focuses on data security and protecting data at rest and in transit, rather than addressing availability. Partitioning generally refers to dividing a database into parts but is not specifically related to high availability mechanisms as in replication.