Virtual servers have proven a boon in the data center but don’t address the challenge of incrementally adding server capacity. The responsiveness and availability of a highly utilized Web application, such as Microsoft SharePoint, can deteriorate when the virtual machine it runs on is out of capacity. Next-generation application delivery controllers (ADCs) not only address this challenge, they interoperate with virtualization tools to provide greater control and even make it possible to automatically deploy server resources based on real-time demand.”]
Source: https://www.csoonline.com/article/2127669/scaling-and-provisioning-virtual-servers.html