Made to Serve

Most virtualization now focuses on the server level. This approach makes a lot of sense because you can use whatever applications you want and pretty much any operating system, and you don’t have to worry about whether or not the applications will behave appropriately. The problem for virtualizing most services is that the protocols (SSH, FTP, etc.) are stateful, and very few are designed with load balancing and failover specifically in mind. Sharing state between servers is a non-trivial problem; sharing the state is simple, but do you take action before or after you have confirmed that the state was shared?