What are Load Balancers and how do they work?

During high loads, such as a large number of parallel accesses, even modern and high-performance Dedicated Servers are unable to process them in a timely manner. A solution to this problem is provided by Load Balancers, which distribute the load across different instances, thereby reducing server response times to a minimum. They allow limiting the loading time even under extreme demand. Load Balancers distribute incoming requests across a connected IT infrastructure and manage connected servers to balance and coordinate them with each other. Equally important is the cache of a website.

What is a Load Balancer?

A Load Balancer is both an algorithm for resource allocation and a higher-level, partially abstracted instance for managing complex and variable scenarios. It allows distributing capacities within a network to multiple machines and coordinating requests according to balanced load balancing. The Load Balancer performs two crucial tasks for an efficient IT infrastructure: managing load distribution on a single server to prevent it from becoming unreachable due to insufficient resources or experiencing degraded server response times, and organizing load distribution within complex systems to ensure each server has identical load and response times.

How does a Load Balancer work?

A Load Balancer handles load distribution by registering requests as they come in and assigning them to a specific instance. The Load Balancing makes this decision based on the current state, both theoretical and practical server response times, and previous decisions on task distribution. Typically, services on a server involve static load distribution without precise predictions, where it's not possible to forecast how long a task will take. Two methods are commonly used for this type of load distribution:

• Randomised distribution based on chance across different instances
• Round Robin method for controlled, step-by-step assignment

At first glance, a random distribution may not seem like a sensible load balancing strategy for optimal server access times . Indeed, this is the case when only a few processes are involved. However, as the number of elements increases and with a similar short processing time, the random method proves to be highly efficient and avoids the need for extensive monitoring. The Round Robin method proceeds systematically by assigning tasks one after the other to the next instance. Once a loop is completed, the Round Robin load balancing starts again with the first instance. Both approaches allow for weighting to favour nodes with low server access times and high performance.

What alternatives to Load Balancers are suitable for load distribution?

Active and organising load distribution is just one method to perform load balancing and ensure low server access times. Another method is based on efficiently separating tasks within the IT infrastructure, for example, through isolating critical computing or security procedures, internal processes, and risk applications such as public connections. This limits the impact of attacks like DDoS to a specific area, ensuring that server access times outside the affected segments are not affected.

Which applications are suitable as Load Balancers?

For load balancing, integration at different levels is recommended. They can be integrated as a module into an Apache 2 server, for example, to directly optimise webpage loading times. Other webservers like NGINX can be used as direct load balancers to distribute requests to other servers. Many providers offer load distribution as an optional service for their own and external Dedicated Servers as well as VPS hosting, so that customers do not have to undertake the often complex installation and configuration themselves and can still benefit from advantages such as fast server access times.

Photo: Markus Distelrath from Pixabay