Load Balancing Software Trends
Load balancing software helps to evenly distribute traffic across your servers, ensuring that no one server becomes overloaded with user requests. With this ability, you can make the most of your existing servers and guarantee the highest level of resource availability for your users.
Modern servers and server farms are receiving more user requests than ever before. With potentially hundreds (if not thousands) of user requests coming in at any given moment, server farms need to be capable of evenly distributing the load across its available resources. By performing this task with load balancing software, modern deployments can avoid overwhelming their servers and maximize uptime.
Load balancing software also offers server farms higher levels of scalability and flexibility. If a server needs to go offline for maintenance, for example, load balancing software will minimize the impact by automatically distributing requests across the remaining servers. Similarly, load balancing software will also redistribute requests with the addition of a new server.
In any case, load balancing software is essential to any server or server farm dealing with high numbers of user requests. As even the most modest server farms begin to handle more user activity than ever, most enterprises will need load balancing to ensure maximum uptime and availability.
Why use load balancing software?
Load balancing software is the most effective way of evenly distributing user requests across your servers, preventing any single server from becoming overwhelmed. Apart from traffic control, load balancing software can also be an effective tool for taking servers down for maintenance and troubleshooting.
Load balancing is typically accomplished using either hardware or software, referred to as “hardware-based load balancing” or “software-based load balancing,” respectively. While both accomplish the same task, software-based load balancing is becoming the industry preference due to its flexibility, scalability, and ease of deployment.
Prevent your servers from being overwhelmed
Every server farm (sometimes known as a server “pool”) has to process user requests—some more than others. While small, low-traffic server farms may be capable of processing most user requests without additional controls, high-traffic server farms don’t have it so easy.
For high-traffic server farms, user requests can come in both trickles and tidal waves; during peak hours, server farms might experience hundreds or thousands of individual user requests at any given moment. Off-peak hours, by contrast, pose little threat to server performance.
During peak hours, servers can’t afford to blindly accept user resources as they come in. Without some form of “traffic control,” spikes in user requests could overwhelm an individual server to the point of crashing, resulting in costly downtime and maintenance.
To help avoid this problem, most system administrators utilize load balancing software to control spikes in user requests. This way, instead of a single spike in requests overwhelming a single server, the requests are evenly distributed across the array of available servers.
As mentioned at the beginning of this section, load balancing is performed with either hardware or software. While many traditional load balancers utilize load-balancing hardware, modern deployments are utilizing software-based load balancing (often in the form of a virtual machine) to do the job.
Perform maintenance and troubleshooting without service disruptions
Load balancing software’s ability to automatically distribute server requests also comes in handy for server maintenance and downtime. Here, instead of having to limit resource availability in the event of downtime, load balancing software can simply redistribute requests across the remaining servers.
In the best of scenarios, downtimes are planned—usually in the event of server maintenance. Ideally, server or network maintenance has a minimal impact on user activity.
To mitigate the impact of downtime, system administrators and technicians usually had to schedule maintenance during off-hours, sometimes during tight time slots in the middle of the night. While these schedules are still necessary for large-scale server maintenance, load balancing software has made them unnecessary for most routine maintenance. Now, instead of having to schedule downtimes, administrators can take servers offline at any time and let load balancing software handle the impact.
In the worst of scenarios, downtimes are unplanned—system failures, security breaches, and other events can cause unplanned downtimes. During peak hours, even the shortest downtimes can lose companies thousands of dollars.
Thankfully, load balancing software benefits these scenarios in the same way it does routine maintenance; if any individual server fails or becomes compromised, administrators can isolate the server without having to worry about the impact on availability. Once again, load balancing software steps in and handles the impact.
While load balancing software extends several benefits to IT staff and technicians, we’ll soon see how the benefits ultimately extend to one group: the users.
Improve user experience and application availability
The ultimate goal of server farms and deployments is to provide some sort of service to users. Whether it’s a software as a service (SaaS), webpage requests, or any other resource, businesses and IT staff have a vested interest in making these resources as available as possible—especially where revenues often depend on it!
With modern technology and infrastructure making more resources available than ever before, users have come to demand an almost “hyper availability” from servers and deployments. Gone are the days of patiently waiting for resources to be available; today’s users want their resources instantly.
Ultimately, maintaining high availability is the responsibility of system administrators and network engineers. While thorough network planning can help, load balancing is usually the most effective tool when it comes to connecting user requests to server farms.
The benefits to users are clear: With each user contributing to potentially hundreds or thousands of requests, load balancing software makes sure that every request is handled equally. Instead of haphazardly allocating requests as they’re received, load balancing software quite literally balances the load, ensuring that every user receives similar levels of availability.
Of course, servers are bound to become overwhelmed at one point—especially during peak hours. Ultimately, server availability is limited to the combined compacity of the entire server farm. If the user requests overwhelm the entire server, then even the most perfect load balancing won’t be enough.
Thankfully, load balancing software can also help in these cases; when more servers and resources are needed to handle growing numbers of user requests, load balancing software can scale with the growth.
Increased flexibility, redundancy, and scalability
Load balancing software is also a useful tool to improve the flexibility, redundancy, and scalability of your server farm. Since load balancing software will attempt to evenly distribute user requests under almost any condition, most software is meant to scale with your network.
This ability has the largest effect on server redundancy. As we discussed earlier, load balancing software will automatically redistribute user requests and traffic to other available servers if one happens to go down. Whether the server is down for maintenance or because of failure, having load balancing software in place to automatically handle the impact satisfies most redundancy requirements.
In other cases, load balancing software also improves the flexibility and scalability of your server farm—even more so than load balancing hardware. Since most load balancing software is contained in a virtual machine, you have the freedom to scale your server farm without having to worry about load balancing.
With software-based load balancing, you can scale your server farm without having to manually change or add existing load balancing hardware. This ability not only helps you adapt to change, but it may also help you make the best of existing resources.
Make the most of your existing resources and avoid unnecessary investment
Load balancing software’s flexibility extends to making the most of your existing server infrastructure. Without load balancing, any-sized server farm would stand the risk of being overwhelmed during peak hours. In these cases, it would be easy to believe that the server farm wasn’t powerful enough to handle the traffic—even if it already was.
Load balancing software is often the key to solving these problems. By simply distributing the load across every server, server farms can handle far more than what they would otherwise be capable of. As a result, system administrators can avoid costly expansions or investments in larger infrastructure.
Simplify server security
The redundancy benefit of load balancing software also makes it an ideal security tool. While not necessarily a security tool in and of itself, load balancing software’s ability to redirect traffic away from compromised servers can help protect the rest of the server farm. With the compromised server safely offline, IT and security staff can handle the issue while the rest of the servers remain unaffected.
Balance application loads
While load balancers of all types distribute user requests, traditional load balancers do so through IP addresses. While this method is effective in many situations, it can be limiting when server-based applications might consume a disproportionate amount of resources.
Enter in application load balancing, a feature included with some load balancing software. By contrast with traditional load balancing, application load balancing directs attention to the “content” of each user request rather than the user itself, handling HTTP headers and cookies rather than just IP addresses. Through this feature, load balancing gains a new level of “intelligence.”
Who uses load balancing software?
While load balancing software is primarily used by IT teams, other network-facing users use load balancing software more than they realize.
IT Teams and System Administrators
There’s no question that load balancing software is an invaluable tool for IT departments, especially network engineers.
Most people in IT are aware of the “CIA triad:” the three-way balance between Confidentiality, Integrity, and Accessibility in any IT deployment. The triad is often visualized as a triangle with each corner representing one of its three values. In practice, when one of these corners is emphasized, the other shrink as a result.
It’s easy to see why this is the case: If an IT team decides to emphasize the Availability of their network, then aspects of the network’s Confidentiality and Integrity could suffer as a result. For example, making the network more Available by allowing users to connect remotely from any device would present significant security risks, thereby sacrificing Confidentiality and Integrity.
Load balancing software is often used as a tool for increasing Availability but it also has a hand in maintaining Integrity. The Availability benefit is easy to see: By evenly distributing user requests across finite resources, users are less likely to encounter long waiting times or service disruptions.
Thankfully, the increased Availability allowed by load balancing software doesn’t come at the expense of Confidentiality or Integrity. By promoting redundancy and effortless compartmentalization, load balancing software promotes all three “corners” of the CIA triad.
Of course, IT departments aren’t glancing over their shoulder at a CIA triad poster every time they make a change in the network. The triad only describes common tradeoffs in IT deployments—it’s not necessarily a rule in and of itself.
Load balancing software also offers a cost advantage over traditional means of load balancing, many of which were hardware-based. With many of these solutions being prohibitively expensive, many IT deployments had to either do without load balancers or find some other means of distributing the load.
With load balancing software, however, IT teams are not only enjoying an affordable load balancing solution, but also one that’s more scalable and flexible than its hardware-based predecessors.
Cybersecurity Teams
While cybersecurity teams usually aren’t responsible for implementing load balancing software, they’re often among its biggest advocates. With compartmentalization and redundancy forming cornerstones of many security strategies, many cybersecurity teams find load balancing software as an effective tool for meeting these requirements.
As we’ve discussed in some of the previous examples, load balancing software automatically redistributes traffic to available servers in the event one (or more) server goes down. This capability is extremely useful in the event of security breaches, as it allows security teams to isolate the affected server without compromising system availability.
Load balancing software also benefits security by offering centralized security functions, such as Secure Socket Layer (SSL) offload (decrypting data). Since load balancing software functions as a “toll booth” for almost all user traffic, many security teams find it effective for centralizing SSL offload and other security functions.
Ultimately: Users
There’s no doubt that load balancing software is an incredibly useful tool for IT and cybersecurity teams. In the end, however, load balancing software is ultimately a useful tool for users.
The very same redundancy and load balancing capabilities that benefit technical departments also benefit the users by further guaranteeing server uptime and availability. Without load balancing software, users wouldn’t be able to access server resources as reliably—especially during peak hours.
Features
Load balancers are either hardware- or software-based. While this isn’t necessarily a “feature” of load balancing software, it’s worth noting the distinction. This guide has been referring to load balancing software as opposed to load balancing hardware, mostly because the software approach has become favorable for most applications.
Load balancing hardware was the traditional method of load balancing server farms. While these were often effective, they also came with several problems: For one, load balancing hardware was prohibitively expensive for many enterprises, often having price tags well into the thousands. Even with this investment, load balancing hardware was also difficult to scale, thereby limiting the growth of many server farms.
By contrast, load balancing software is often very inexpensive—even by software standards. Plus, since many software packages take the form of a virtual machine, most modern load balancing software scales effortlessly with your server farm. As a result, you’ll want to choose software-based load balancing for most applications.
Load balancing software packages can be either installable or managed services. While this is true for most software packages (load balancing or not), you’ll want to choose the option that best fits your needs and resources.
Choosing a traditional installable solution may offer more flexibility, but it will still require initial configuration and long-term management—something which some organizations might not have the resources to handle. By contrast, choosing a managed service (e.g. “load balancer as a service” or LBaaS) can help avoid complicated and time-consuming configurations, albeit at some loss of control and latency.
Load balancing software should utilize a common load balancing algorithm (or give you the choice). Load balancers utilize special algorithms for efficiently distributing traffic. While several of these algorithms exist, the most common include:
Round Robin: Probably the most common default algorithm for load balancing software. Here, the round robin algorithm simply “rotates” around available servers, sending one request to each server at a time. The algorithm assumes that every user request has the same “load—” something which might not be true in every network.
Weighted Round Robin: A more flexible version of the traditional Round Robin algorithm; instead of sending one request to one server at a time, each server is assigned a different “weight” corresponding to the number of requests it can receive at a time. So, if a server is assigned a weight of “two,” for example, it will receive two user requests per turn. This algorithm is useful for server farms whose servers don’t have the same processing capacity.
Least Connections: Requests are directed to the server with the fewest connections. Like the Round Robin algorithm, it also assumes that each user request carries the same load.
Least Time: Requests are directed to the server with the fastest response time and fewest connections. Mostly utilized by NGINX.
Hash: Hashing algorithms “link” clients and servers through a hash-based key, sometimes done through their IP addresses (IP Hash). This algorithm allows users to maintain connectivity with a particular server even if the connection is dropped.
Session Persistence: Sometimes known as “sticky sessions,” session persistence links a client with a particular server for the duration of the session— a kind of persistence not always guaranteed by other algorithms. “Sticking” with the same server in this way improves both user experience and network response times.
Load balancing software typically utilizes TCP/IP network protocols. These are among the most common protocols in any network, and most load balancing software uses them to assign identities to clients and servers. As discussed in the previous feature, IP is also used for the IP hash algorithm.
Load balancing software should be compatible with existing infrastructure, particularly your hardware. This point should almost go without saying, but compatibility is crucial to the effectiveness of any load balancing software installation. Just like any other software package, it’s crucial to make sure the package you choose is compatible with your existing infrastructure, hardware, and operating systems; after all, they’ll be having a very close relationship!
Thankfully, many load balancing software packages are compatible with most major operating systems and network infrastructure. Even those that aren’t can be implemented via virtual machines, allowing you even greater flexibility. However, it’s still important to double-check before you buy.
FAQ
Q: What is load balancing?
A: Load balancing is the process of evenly distributing user requests across multiple servers, ensuring that no one server is overwhelmed. While this process was traditionally performed using load balancing hardware, most modern solutions implement load balancing software.
Q: What is load balancing software? How is it different from load balancing hardware?
A: Load balancing software performs load balancing across your network, usually existing as a virtual machine among your server farm or as a managed service deployed from the cloud. Load balancing software utilizes various algorithms to evenly distribute user requests between servers.
By contrast, load balancing hardware is physical hardware/firmware serving as a direct intermediary between clients and servers. Load balancing hardware is often expensive and difficult to scale, which has resulted in it falling out of favor in many IT deployments.
Q: What are the benefits of using load balancing software?
A: By evenly distributing user requests across available resources (servers), load balancing software helps improve user experience and network availability. This capability also makes it easier to take servers down for maintenance without sacrificing resource availability.
Recap
Load balancing software evenly distributes user requests across your server farm, thereby making the most of your existing resources and avoiding server crashes. While load balancing was traditionally performed with costly hardware, load balancing software now provides a low-cost, flexible solution that almost any network can adopt. Load balancing software can also improve your server farm’s redundancy and security by automatically redirecting user requests away from downed servers.
