Every year, global enterprises suffer application downtime due to failures in software or infrastructure, whether the applications are in secure data centers, or in public clouds. However you measure it, the cost of application downtime can be very high for many organizations. For enterprises that provide online services and applications, the cost of downtime impacts revenue, sales and customer loyalty.
Global Load Balancing is often used to improve application response and service continuity for geographically-distributed customers. Pulse Secure Virtual Traffic Manager can help to optimize service response times, as well as simplify failover and recovery, giving a real-time response to application workloads or service outages.
Server Load Balancing Within a Data Center
There are two commonly used techniques to minimize the chance of a failure causing downtime in network-based applications. These are Server Load Balancing and Global Load Balancing.
Techniques like server load balancing and clustering are often used within a data center to build clusters of fault-tolerant, scalable applications. These clusters are resilient to isolated failures—for example, when a server develops a hardware fault. Clusters also make it easy to add more capacity to an application to meet growing demands. However, a clustered, fault-tolerant application running in a single data center is still vulnerable to downtime:
- The application may fail because of a single, critical point of failure such as a database or SAN, or it may fail because of administrator error
- The data center may be disrupted due to a catastrophic natural or man-made disaster, such as power failure because of rolling blackouts, maintenance errors or even malicious attack
- The data center may become unavailable because of a denial-of-service attack mounted against a different service running in that data center, or because of a failure in local network connectivity.
Organizations who wish to protect against these risks often choose to deploy a Global Load Balancing solution which routes application traffic to multiple distinct data centers and removes the single point of failure.
Global Load Balancing Between Data Centers
Global Load Balancing (GLB) systems manage how clients are connected to a data center, when a service is hosted in multiple distinct data centers.
- In an Active-Passive configuration, one data center is nominated the active one for each service. The other data centers are idle for that service. If the active data center becomes unavailable, one of the passive data centers becomes active and all clients are directed to it.
- In an Active-Active configuration, all data centers are used and clients are load-balanced between them based on data center performance and proximity
The primary purpose of a GLB system is Business Continuity—to ensure that services are always available, even when one or more service locations (data centers) becomes unavailable.
A second purpose of GLB is to Improve Customer Experience—to load-balance each user to the best data center from a choice of several. The choice can be based on data center performance and proximity, so that clients are directed to the data center that is closest and is performing the best, so that clients gets the best possible level of service.
A GLB device can direct users to the closest data center for best levels of service
Who Might Use a Global Load Balancing Solution?
A GLB solution is relevant to:
- Organizations which provide or depend on an online service, such as a public-facing Web site, or a network-based application for internal use
- Organizations which cannot tolerate service failure, whether this results in lost productivity, lost revenue, or lost customers
- Organizations which need to improve the SLA (Service Level Agreement) with its users or customers, providing them with a superior and competitive level of service