What is Load Balancing?

Mission critical web-based applications with heavy workloads require a High Availability (HA) solution. Rackspace Cloud Load Balancers distribute the workload across two or more servers, network links, and other resources to maximize throughput, minimize response time, and avoid overload. You can quickly load balance multiple Cloud Servers or external servers for optimal resource utilization. Read more to see how easy this is to do! 

Creating a Load Balancer

1. Log into the New Cloud Control Panel and click Load Balancers at the top of the page.
2. Click Create Load Balancer. The Create Load Balancer page looks like this:

3. Enter the Name for the Load Balancer. There are no limitations on the text in this field and you can name the Load Balancer whatever you choose.
4. Select the Virtual IP:

• Accessible on the Public Internet — This setting for VIP type allows any two servers with public IP addresses to be load balanced. These can be nodes outside of the Rackspace network, but please be aware that standard bandwidth rates will apply.
• On the Private Rackspace Network — This is the best option for load balancing two Cloud Servers, as it allows the load balancing traffic to run on the Rackspace Cloud Internal Network, also known as ServiceNet. This option has two distinct advantages: the rate limit is double what the rate limit is on the public internet, and all traffic on ServiceNet between Cloud Servers is not charged for bandwidth.

5. Specify the Protocol / Port:

• Select the Protocol using the drop-down menu. 
• The pre-configured Port for that protocol is then specified automatically. If you are running a service on a non-standard port and need to load balance it, you can modify the Port number as needed.

6. Select the Algorithm. In most cases, the Random, Round Robin, or Least Connections algorithms will be sufficient when load balancing two identical nodes for increased web traffic. If your nodes are unequal in size or resources, you should take a look at using weighted algorithms to favor your nodes with more resources. The algorithm specifies how traffic should be directed between nodes:

• Round Robin — Connections are routed to each of the nodes in turn. 
• Weighted Round Robin — A round robin algorithm, but with different proportions of traffic being directed to the nodes. Weights must be defined as part of the load balancer's node configuration.
• Random — Nodes are selected at random.
• Least Connections — The node with the lowest number of connections will receive requests.
• Weighted Least Connections — Each request will be assigned to a node based on the number of
  concurrent connections to the node and its weight.

7. Select the Region: 

• Your load balancer can be provisioned in Dallas, TX (DFW) or Chicago, IL (ORD).
• When selecting a region, consider the location of the nodes you want to load balance and provision your load balancer in a region that is geographically as close to your nodes as possible.

8. Add Nodes to your load balancer:

• Click Add Cloud Servers to add Cloud Servers to your load balancer. Check the check boxes for the Cloud Servers to add to your load balancer. Then click Add Selected Servers.
• Click Add External IPs to add external nodes to your load balancer. Specify the IP Address, Port, and Weight for the specified external node. Then click Add External IP.

9. When you are finished adding nodes, click Create Load Balancer.

Your load balancer is then created. A success message is briefly displayed, and your load balancer is displayed with its Name and Protocol/Port in the list of Load Balancers. 

Modifying a Load Balancer Using the Actions Cog

Modify a load balancer by clicking the Actions cog to the left of the load balancer name in the list of Load Balancers. Then select the desired action from the drop-down menu. 

Viewing the Details of a Load Balancer

To view the details of a load balancer, follow these steps:

1. Click the Load Balancers button at the top of the New Cloud Control Panel. 
2. A list of the load balancers for your account is displayed.
3. Click the Name of the load balancer to view.

The status and details for the load balancer are displayed. From this page you can:

• Add Nodes to the load balancer by clicking Add Cloud Servers or Add External IPs:
  • Add Cloud Servers — Click the check box(es) for the Cloud Server(s) to add. Then click Add Selected Servers.
  • Add External IPs — Enter the IP Address and Port for the external IP to add. Then click Add External IP.

Modify a Load Balancer by selecting an action from the Actions drop-down menu.
 

Modifying a Load Balancer Using the Actions Menu

Modify the selected load balancer by choosing the desired option from the Actions menu:

• Rename Load Balancer — Type a new name for the load balancer in the highlighted field and then press Enter.
• Edit Protocol / Port — Select the desired Protocol from the drop-down menu. The pre-configured Port for that protocol is then specified automatically. If you are running a service on a non-standard port and need to load balance it, you can modify the Port number as needed. Then click Save Protocol / Port.
• Edit Algorithm — Click the radio button for the desired algorithm to select it. Then click Save Algorithm.
• Delete Load Balancer — Confirm the delete message displayed iby clicking Delete Load Balancer.
• Add Cloud Servers — Click the check box(es) for the Cloud Server(s) to add. Then click Add Selected Servers.
• Add External IPs — Enter the IP Address and Port for the external IP to add. Then click Add External IP.
• Edit Health Monitoring — Specify the desired information for the health monitor:
  • Monitor Type — Select the desired monitor type from the drop-down menu.
  • Delay — Enter the minimum number of seconds to wait before executing the health monitor.
  • Timeout — Enter the minimum number of seconds to wait for a connection to be established before timing out.
  • Attempts Before Deactivation — Enter the number of permissible monitor failures before removing a node from rotation.
  • Path — Enter the HTTP path that will be used in the sample request.
  • Status Regex — Enter a regular expression that will be used to evaluate the HTTP status code returned in the response.
  • Body Regex — Enter a regular expression that will be used to evaluate the contents of the body of the response.

     When you are finished editing the settings for the health monitor, click Save Health Monitor.

• Edit Connection Throttling — Specify the settings to control performance and abuse from a single IP:
  • Max. Connections — Enter the maximum number of simultaneous connections.
  • Threshold — Enter the threshold for the number of simultaneous connections allowed from any IP.
  • Limit to — Enter the number of new connections allowed within the next time frame.
  • Timeframe — Enter the timeframe length in seconds to use for counting new connections.

     When you are finished editing the settings for connection throttling, click Save Connection Throttling.

• Enable Session Persistence — Click Enable Session Persistence to have the load balancer redirect subsequent requests to the same node.
• Edit Logging — Click Enable Logging to process log files every hour and store them in your Cloud Files account at the standard storage rate.
• Edit Error Page — Click the desired radio button to select the type of error page this load balancer displays. Then click Save Error Page.
• View Rules — Display the rules for allowing or denying access to this load balancer for IPs and networks.
• Add Rules — Click Add Rule to create a rule to specify the IPs or networks that are allowed or denied access to this load balancer. Enter the IP addresses, separated by commas, and then select Allow or Deny from the menu. Click Save.