Adding Additional Servers to Load Balancers

From GoGrid

Introduction

The GoGrid user-interface does not provide the ability to edit an existing Load Balancer's configuration to add additional servers to the pool. This guide is a temporary fix to provide that ability while experiencing minimal downtime. The GoGrid development team has plans to release a feature allowing existing Load Balancers to be edited sometime between Q4 '08 and Q1 '09.

If you have an existing Load Balanced network and wish to add an additional server to be Load Balanced, this guide is for you.

How it Works

Adding a new server to a Load Balancer's pool is actually quite simple. To do this, simply create a new Load Balancer by adding all of the IP's you want to Load Balance (new and old) to the pool in the user interface:

1. Click on the " + /add" button from the Grid menu
2. Select "Load Balancer"
3. The "Add Load Balancer" window will open
4. Provide a name and description for the Load Balancer (you can have multiple instances of Load Balancers, all for different purposes)
5. Wait until step 12 to add a "Virtual IP" from the list of available IP's at the left of screen.
6. Add a "Virtual Port" number for the port you wish to balance.
7. Add "Real IP's" and "Real Ports" to the pool. These are the IP addresses and corresponding ports you wish to Load Balance. The system will automatically suggest the IP addresses you currently have deployed on the grid. Be sure to add IP's for the original servers and the new servers you wish to add to the pool.
8. You can add additional IP's and ports to the pool by clicking on the "+" button or by tabbing down a line.
9. Select the type and persistence for the Load Balancing Algorithm. This will most likely match the persistence of the existing Load Balancer.
10. DO NOT save your configuration yet. Open another my.gogrid.com session in a new browser window or tab.
11. Make note of the virtual IP assigned to the old Load Balancer and delete it.
12. Wait 30 seconds or so and go back to the original my.gogrid.com browser session. Change the virtual IP on the "Add Load Balancer" window to point at the same IP as the old Load Balancer.
13. Click "Save" and your Load Balancer should be completely deployed in under a minute. Your total downtime will begin from the time you delete the old Load Balancer until the new Load Balancer is fully deployed.

If you have your DNS setup to point to the virtual IP of the Load Balancer, you must ensure that the above process is followed step-by-step. Assigning a new virtual IP to the new Load Balancer will require DNS changes and will exponentially increase your down time. If you accidentally hit "Save" in step 5, request a DNS change to point at the new virtual IP. Please note that DNS changes can take up to 24 hours to process. You can create a new DNS request by clicking on the "Manage" link on the Network Widget from the Grid tab.