Understanding Load Balancing for Web Servers
Websites and applications with a large amount of traffic will benefit from load balancing. We will dive into what it is, the methods of load balancing, its benefits, and its uses for load balancing.
This article will focus on balancing hypertext transfer protocol (HTTP) and hypertext transfer protocol secure (HTTPS) traffic through a load balancer.
What is Load Balancing?
Load balancing is the distribution of website or application workloads across multiple servers (sometimes called nodes). Traffic is intelligently distributed across these servers to a single IP using different protocols. As a result, the processing load is shared between the nodes rather than being limited to a single server, increasing the performance of your site or application during times of high activity.
Load balancers are implemented via hardware or software. For example, in web hosting, load balancing is typically used for handling HTTP traffic over servers acting together as a web front-end. The web front-end comprises the graphical user interface (GUI) of a website or application.
Load balancing also increases the reliability of your web application or website and allows you to develop them with redundancy in mind. If one of your servers fails, the traffic is strategically distributed to your other nodes without interruption of service.
Methods of Load Balancing
There are different algorithms used to balance your traffic. Each has advantages and drawbacks.
With the round robin method, the load balancer will send traffic to each server in succession. Round robin is most effective on equally-configured web servers and when concurrent connections are not extremely high. The load balancer will evenly distribute traffic but does not consider the nodes’ current load, open connections, or responsiveness.
The least connection method considers the current number of open connections between the load balancer and the server. It sends the traffic to the node with the lowest number of active connections. Thus, it is most effective with higher concurrent connections. The least connection method is more intelligent than the round robin method but still does not consider the current load or responsiveness of the nodes.
Least Response Time
The least response time method decides which node to send the traffic to using the current number of open connections between the load balancer and the server and the response times of the nodes. Thus, the node with the lowest average response time and the fewest number of active connections receives the traffic.
The hashing method of load balancing distributes traffic based on a defined key from the connection or header information of the incoming request. For example, a load balancer using the hashing method will examine the incoming data packets and distribute traffic based on the source or destination IP address, port number, uniform resource locator (URL), or domain name.
Benefits of Load Balancing
By nature, load balancing solves more than one problem:
- Unexpected traffic spikes.
- Growth and popularity over time.
Here are some additional benefits of load balancing.
As your website or application grows, your load-balanced infrastructure grows with you. Add additional web server nodes to increase your capacity to handle the added traffic.
Your web front-end is replicated across your web servers, giving you redundancy in case of node failure. The remaining servers handle your traffic if an issue occurs until the failed node is repaired or replaced.
The fact that there are several load balancing methods means that options abound for managing traffic flow. You have the flexibility to choose how you want incoming requests to be distributed.
Drawbacks of Load Balancing
While there are a lot of benefits to load balancing, there are some disadvantages as well.
The method or algorithm of load balancing that you choose may not consider the nodes’ current load, open connections, or responsiveness. This lack of consideration means that the node receiving the traffic could already be under significant load, have little to no available connections, or be unresponsive.
Another drawback is the possibility of additional configuration depending on the implementation of your load-balanced infrastructure. For example, it may be necessary to maintain concurrent connections between website/application users and servers. Also, as servers are added or removed, you will need to reconfigure the load balancer.
There are additional costs associated with hardware-based load-balanced infrastructure. For example, you will need to account for the cost of additional servers for the dedicated load balancer and the web nodes.
Load Balancing Use Cases
The redundancy of load balancing allows you to limit the points of failure in your infrastructure. Doing so increases your uptime. For example, suppose you load balance between two or more identical nodes. In that case, if one of the nodes in your Liquid Web server cluster experiences any kind of hardware or software failure, the traffic is redistributed to the other nodes to keep your site up.
If you are focused on uptime, load balancing between two or more identical nodes that independently handle the traffic to your site allows for failure in either one without taking your site down.
Plan for Future Growth
As your site gains popularity, you will outgrow the power of even the most robust servers and require something more substantial than a single server configuration. Load distribution helps you grow beyond a single node.
Upgrading from a single server to a dual server configuration (one web server and one database server) will only allow for so much growth. It is useful when your backend database is receiving a ton of requests and needs its own resources to handle them. When the issue is related to the front-end, load balancing the traffic will aid in the growth you are experiencing.
Predictable and Actionable Analytics
More than directing traffic, software load balancers give insights that help spot traffic bottlenecks before they occur or become more significant issues. Being able to see where traffic is or potential holdups will save time and money. In addition, it gives you actionable predictions and analytics that help you make informed business decisions.
Choosing the Best Method for You
The most appropriate choice in load balancing algorithms depends on the needs of your website or application. If your site is experiencing slow performance due to concurrent connections, it is worth exploring load balancing options.
Liquid Web has load balancing, Dedicated Server options, and more available. Consult with our solution architects and hosting advisors to answer any questions about what is best for you. Schedule a call today!
About the Author: Ronald Caldwell
Ron is a Technical Writer at Liquid Web working with the Marketing team. He has 9+ years of experience in Technology. He obtained an Associate of Science in Computer Science from Prairie State College in 2015. He is happily married to his high school sweetheart and lives in Michigan with her and their children.
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