## High Availability Load Balancing High Availability Load Balancing (HALB) is an appliance that provides load balancing for RAS Secure Client Gateways. A Parallels HALB appliance is a preconfigured virtual machine with the operating system installed and all relevant settings configured. Parallels HALB appliance is available for the following hypervisors: Microsoft Hyper-V VMware Citrix Hypervisor HALB deployment in Parallels RAS is per Site, which means that a Site must have at least one Parallels HALB appliance deployed. Since HALB is a single point of contact for the client software, it is recommended to have at least two HALB appliances per Site for redundancy. Multiple HALB deployments can run simultaneously, one acting as the primary and others as secondary. The more HALB deployments a Site has, the lower the probability that end users will experience downtime. Primary and secondary HALB deployments share a common or virtual IP address (VIP). Should the primary HALB deployment fail, a secondary is promoted to primary and takes its place. Note: Please note that when a secondary HALB deployment is promoted to primary, a user will experience two disconnects: one when the primary HALB deployment goes down and one more time when it goes back up since VIP moves from one deployment to the other. Setting up High Availability Load Balancing consists of the following steps: Deploying a Parallels HALB appliance. Configuring HALB in the RAS console. Read on to learn how to download and deploy a Parallels HALB appliance.