How is redundancy handled in distributed web systems?

Redundancy in distributed web systems is handled through replication and load balancing techniques.

In distributed web systems, redundancy is a critical aspect that ensures reliability, availability, and fault tolerance. Redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the form of a backup or fail-safe.

One of the primary ways to handle redundancy is through replication. Replication involves creating multiple copies of data and storing them in different locations. This ensures that even if one server fails, the data is not lost as it is stored in other servers. Replication can be done in real-time (synchronous replication) or at scheduled intervals (asynchronous replication). Synchronous replication ensures that all copies of the data are identical at all times, but it requires more resources and can slow down the system. Asynchronous replication, on the other hand, allows for slight differences between the copies of data, but it uses fewer resources and does not slow down the system as much.

Another method to handle redundancy is through load balancing. Load balancing is the process of distributing network traffic across multiple servers to ensure that no single server bears too much demand. This not only ensures that the system can handle high traffic without crashing, but it also allows for redundancy. If one server fails, the load balancer can redirect traffic to the other servers, ensuring that the system remains up and running.

In addition to replication and load balancing, distributed web systems can also use techniques like sharding, where data is split into smaller, more manageable parts, and each part is stored on a different server. This not only helps in handling large amounts of data but also adds another layer of redundancy.

In conclusion, handling redundancy in distributed web systems is a complex task that involves a combination of various techniques. The goal is to ensure that the system remains reliable and available, even in the face of server failures or high traffic.