The potential cost of an outage due to the failure of a key application server is significant with research from the Aberdeen group putting the hourly cost for a small business at over $8,000. The actual cost incurred will vary between organizations but the basic fact remains that outages cause customers to go elsewhere, leave employees idle and frustrated and can be extremely damaging to a business reputation. It is imperative that businesses assess the impact of a failure and take appropriate steps to minimize the risk of a server failure.
One approach to deal with this problem of server failure is to buy bigger and more expensive servers with dual power supplies, redundant storage. However, such systems are still prone to failures of components other than the hardware. An alternative approach to the big box approach is to use multiple servers fronted by a load balancer. In this scenario, the load balancer not only spreads traffic between servers, but in the event of a server failure, will detect the failure and redirect traffic to healthy servers.
Load balancing also simplifies the challenge of adding capacity and scaling to meet changing demands. Rather than being in a constant upgrade cycle, servers can seamlessly be added and removed totally transparent to the users. This reduces the risk of having to do big-bang upgrades and also provides the flexibility to grow as demands change.
Load balancers can be deployed as dedicated appliances or as virtual appliances. In both cases, the load balancer can be deployed as a highly available (HA) pair to avoid having a single point of failure. Hardware load balancers provide guaranteed levels of performance and are not impacted by other workloads on the virtual infrastructure. Virtual appliances run on existing hypervisor platforms such as HYPER-V and VMWare or on cloud platforms such as Azure and AWS. With Kemp, the same software drives both hardware and virtual appliances offering a consistent administration interface.
You can use hardware or software based load balancers. The good news for the IT manager is that some load balancing vendors offer both solutions, such as Kemp Technologies. In some cases, the GUI and functionality of both software and hardware based load balancers is identical. Load balancers are platform and protocol independent and by their nature they are agentless. No special configuration is therefore necessary, because the load balancers are not part of the server clusters, but rather they sit in front of them.
A lot of factors come into play when sizing a load balancer. Some application clients, such as Microsoft Exchange for example, establish multiple connections to multiple servers and have a different traffic profile than a simple website application. Kemp provide sizing tools (such as the Exchange 2016 interactive Sizing Guide) and pre-sales assistance to assist in sizing load balancers correctly for your workloads.