Load balancing is the method of dividing the total amount of work performed by one computer between two or more computers. Its aim is to get more work done in the same amount of time, ensuring that all the users get served faster.
Load balancing distributes various workloads across multiple computing resources, which usually include network
links, disk drives or central processing unit apart from multiple computers. It can be implemented with software, hardware or a combination of both. It also increases availability and reliability.
Two questions surrounding the topic of load balancing usually include — a)
‘Do I really need to do it?’ and b)
‘When do I need to do it?’ Both the questions can be answered in one word — a)
Yes and b)
Always. In fact, local load balancing is an absolute must for two important reasons.
1.To Achieve Availability and Scalability
In every business, growth is a priority. To ensure that you achieve high availability that is sustainable, you would need a minimum of two backend servers. The load balancer
will make sure that if one backend isn’t functioning properly, all the traffic gets diverted to the other backend.
2.To Put a Control Point in Front of your Services
This advantage doesn’t concern with distributing or balancing the load. Ideally, you should use a load balancer even if you have a service with a single backend. When you have a control point, it gives you the ability to change the backends during various deploys. Additionally, it also allows you to add filtering rules and enables you to manage your traffic flow efficiently. You can change the way your service is implemented on the backend without risking exposing those changes to consumers using your service on the front-end.
Make Load Balancing an Easy Task
Since load balancing is an extremely crucial aspect, it should be easy for the users to create a load balancer. Provide people with a lightweight software load balancer or virtual setup associated with a hardware load balancer as part of their application. Since each application needs a load balancer, your system should include it automatically for providing an app. It can either be deployed as a software or a configuration within a hardware load balancer. You can choose from a number of technological approaches to achieve effective and easy-to-use load balancing.
Tackling Load Balancing Issues
While the advantages of using a load balancer are many, it does come with some concerns too. The main issue is that you are basically creating a single point of failure in the architecture. If there are several backend web servers and one of them fails, then it won’t interrupt the service as the other servers handle the traffic. However, if there one load balancer and it fails, then the whole tier would be affected. Your load balancer has to be extremely sturdy and robust so that the chances of the failure are drastically reduced. Multiple load balancers must be deployed in a high-availability manner. We can minimize load balancing concerns by adopting some practices that include:
a) Using Border Gateway Protocol (BGP) Internally
By using BGP internally, every load balancer can publish a route to the virtual IP that is being used for the service. Then, your routers can choose which routes can serve the traffic. This will ensure that the routers perform a balancing on an IP level to HTTP load balancers and ensure that you can always reach an HTTP load balancer. From HTTP load-balancers, they can perform HTTP proxy-type balancing into the web backends, thus giving a highly available load balancer tier and servers.
b) Filtering Logic and other Behavioral Rules in the Load Balancing Tier
This helps in ensuring that tracking headers are in place for managing internal traffic. Furthermore, you can implement rate limits to cater to the traffic coming from outside. You can blacklist those trying to access the system or to route requests to new services.
In part two of this post, we will talk about global load balancing. It’s popular for its disaster recovery functionality and for a more intelligent direction of traffic for optimal site selection. It is more complex as it moves traffic between multiple data centers.