Virtualization has become the new computing cluster. Clustering--the ability to have two or more computers operate in lockstep for highly available systems--has been around since almost the earliest PC and mainframe days. But a new take on clustering is emerging that leverages virtualization tools and is becoming more appealing, particularly as enterprise IT shops gain more experience using virtual servers and as virtualization vendors add more high-availability features to their products. Virtualization, along with cloud computing, is becoming the new way to provide redundant services, and as such is making it more affordable and within the reach of businesses without a lot of IT expertise.
PC clustering used to be a very specialized discipline. You needed to set up nearly identical computers and run special operating system versions to keep them synchronized. They required special networking adapters to move data between the two PCs at very high speeds. But networks have gotten faster, so that gigabit or better Ethernet is now found on most desktops and servers. And a combination of services, including high availability, virtual storage management, and near-term server failover that were previously only the province of very expensive and customized clustered configurations, are now available in the virtual world and can serve as a good substitute for many enterprise's disaster recovery (DR) applications, too.
Clustering used to involve specialized tools and a dedicated network to handle failovers. Now with various virtualization products, it is a lot easier to provide similar service levels for a wider collection of computing needs.
Certainly, virtualization is on the rise for many enterprises: a combination of better resource use, reduced power and cooling in the data center, and more manageable application delivery have made it a very popular solution recently. And as IT shops gain more expertise in delivering virtualized applications, they have seen that they can also get a better handle on how to leverage this expertise to deliver clustering solutions.