In the comments to my previous post about the real promise of cloud computing, I had a request to talk some more about DNS based load balancing. I’m going to look at different load balancing techniques and how they can expand or transition your physical data center to cloud computing.
DNS round robin load balancing is the old school way to do this. Multiple A records are added to the DNS server for a particular host name and the DNS server rotates through the different addresses on every look up request. TTL (time to live) entries are typically set very short to allow the traffic to rotate fairly evenly.
The problem with this is DNS servers that ignore the short TTL and cache look ups based on their own criteria. This distorts the load balancing and can even create inaccurate results, breaking access to the service for users using that particular DNS server. Given the lack of control over other DNS servers cache policy, DNS load balancing can be problematic at the very least.
On our cloud computing service, the basic load balancer cloudblock uses the Linux balance package. Balance uses active routing to split traffic between multiple servers and failover servers without any DNS contortions at all (we use balance in front of our own servers). Balance is also ridiculously easy to configure.
For more complex and higher traffic needs, a caching proxy load balancer such as Apache traffic server is more appropriate. We also offer traffic server as a preloaded cloudblock on our cloud computing service.
Using the load balancer cloudblock also makes it simple to expand or smoothly transition your physical servers to the cloud service. To use the cloud for expansion, take a load balancer cloudblock and use it to route the traffic to one or more physical servers. When you need more capacity, turn up a virtual web server cloudblock, upload your web site to it, and add it to the load balancer. Dealing with unexpected load is now nothing more than a 10 minute exercise in easy, seamlessly integrating both cloud and data center services.
To smoothly transition a physical server to the cloud, take a load balancer cloudblock and use it to route the traffic to the physical server. Turn up a virtual web server cloudblock, upload the site to it, and test to make sure it will operate properly, then add it to the load balancer. When you have the comfort level that everything is operating reliably and correctly, remove the physical server from the load balancer. You’ve now just migrated a running service with no impact at all to your users and without having to risk an all or nothing flick of the switch.
Integrating cloud computing services to augment your existing data center or smoothly move services back and forth really is just that easy.
Why are you waiting? Go cloud today!
Email or call me or visit the SwiftWater Telecom web site for cloud computing services!