In the cloud, simple will be big

The cloud uses virtualized computers, usually virtualized PCs or PC-based servers.

The temptation is to build (well, instantiate) larger virtualized PCs. More powerful processors, more cores, more memory, more storage. It is a temptation that is based on the ideas of the pre-cloud era, when computers stood alone.

In the mainframe era, bigger was better. It was also more expensive, which in addition to creating a tension between larger and smaller computers, defined a status ranking of computer owners. Similar thinking held in the PC era: a larger, more capable PC was better than a smaller one. (I suppose that similar thinking happens with car owners.)

In the cloud, the size of individual PCs is less important. The cloud is built of many (virtualized) computers, and more importantly, able to increase the number of these computers. This ability shifts the equation. Bigger is still better, but now the measure of bigger is the cloud, not an individual computer.

The desire to improve virtual PCs has merit. Our current virtual PCs duplicate the common PC architecture of several years ago. That design includes the virtual processor type, the virtual hard disk controller, and the virtual video card. They are copies of the common devices of the time, chosen for compatibility with existing software. As copies of those devices, they replicate not only the good attributes but the foibles as well. For example, the typical virtualized environment emulates IDE and SCSI disk controllers, but allows you to boot only from the IDE controllers. (Why? Because the real-world configurations of those devices worked that way.)

An improved PC for the cloud is not bigger but simpler. Cloud-based systems use multiple servers and "spin up" new instances of virtual servers when they need additional capacity. One does not need a larger server when one can create, on demand, more instances of that server and share work among them.

The design of cloud-based systems is subtle. I have asserted that simpler computers are better than complex ones. This is true, but only up to a point. A cloud of servers so simple that they cannot run the network stack would be useless. Clearly, a minimum level of computation is required.

Our first generation of virtual computers were clones of existing machines. Some vendors have explored the use of simpler systems running on a sophisticated virtualization environment. (VMware's ESX and ESXi offerings, for example.)

Future generations of cloud computers will blur the lines between the virtualization manager, the virtualized machine, the operating system, and what is now called the language run-time (the JVM or CLR).

The entire system will be complex, yet I believe the successful configurations will have simplicity in each of the layers.