Resource Based & Round Robin Load Balancing

Load Balancer is designed to balance RDS and VDI host connections made from Parallels Clients.

The following types of load balancing methods are available:

• Resource Based. Distributes sessions to servers depending on how busy the servers are. Therefore a new incoming session is always redirected to the least busy server.
• Round Robin. Redirects sessions in sequential order. For example the first session is redirected to server 1, the second session is redirected to server 2 and the third session is redirected to server 1 again when there are two terminal servers in the farm.

Both methods are explained in this and the following subsections.

Load Balancing options can be configured from the Load Balancing category in the RAS Console.

Enabling Resource Based Load Balancing

Load balancing is enabled by default when more than one server is available on the site. The resource-based load balancing is the default method.

To switch back to resource-based from round-robin load balancing, select Resource Based in the Method drop-down list.

Configuring Resource Counters

Resource-based load balancing uses the following list of counters to determine if a server is busier than the other/s and vice versa:

• User sessions. Redirect users to a server with the least number of sessions
• Memory. Redirect users to the server with the best free/used RAM ratio
• CPU. Redirect users to the server with the best free/used CPU time ratio

When all of the counters are enabled, the RAS LoadBalancer adds the counter ratios together and redirects the session to the server with the most favorable combined ratio.

To remove a counter from the equation, clear the checkbox next to the counter name in the Counters section.

Round Robin Load Balancing

Round-robin load balancing redirects sessions in sequential order. For example, with two RDS servers in the farm, the first session is redirected to server 1, the second session is redirected to server 2, and the third session is redirected to server 1 again.

Enabling Round Robin Load Balancing

To enable round-robin load balancing select Round Robin in the Method drop-down list.

Session Options

Reconnect to Disconnected Sessions. Enable this option to redirect incoming user sessions to a previously disconnected session owned by the same user.

Reconnect sessions using client’s IP address only. When reconnecting to a disconnected session, the Parallels Remote Application Server will match the username requesting to reconnect with the username of the disconnected session to match the sessions. With this option enabled, the Parallels Remote Application Server will determine to which disconnected session to reconnect the session by matching the source IP address.

Limit Number of Sessions for Users. Enable this option to ensure that the same user does not open multiple sessions.