Virtual machines bring an entire new level of possibilities to computing -- both literally and figuratively. The most significant gain would likely be that of being able to perform significantly more work, on multiple different operating system platforms, using the same hardware that once would have utilized a single OS. This technological innovation is made possible by the creation of virtual machines, each operating as a fully independent server, all relying on a single hardware platform.

It should not be considered, however, that moving onto a virtual platform leaves behind all previous issues associated with hardware-only computing. In fact, there are numerous problems that can occur with virtual environments that have their roots in age-old maladies.

A system administrator, moving onto a virtual platform for the first time, might for example encounter I/O bottlenecks -- meaning, there seem to be a significantly excess number of read and write I/Os compared to the number of files actually being read and written. Along with this, users might complain of slow virtual machine performance which, of course, begins to defeat one of the very reasons VMs were implemented to begin with. The very first scheduled backup takes far longer than it should, with no apparent reason.

All of these issues can be traced back to one single problem: file fragmentation. Most IT personnel will be familiar with fragmentation; originally developed to make better use of disk space, fragmentation splits a file into thousands or tens of thousands of fragments, requiring enormous I/O traffic to handle them all when reading or writing. Fragmentation is probably the number one enemy of performance.

In a virtual environment, fragmentation does not only occur at the host level; logical file fragmentation also happens within every virtual machine. The result is a rapid bottlenecking of I/O bandwidth, creating a variety of performance problems. A significant loss in data throughput occurs on virtual machines regardless of underlying storage infrastructure. When bottlenecks occur in a shared virtual environment, the entire environment is affected -- not simply the source OS.

Because they weren't designed for virtual environments, simple defragmentation solutions won't properly address the problem. A full virtual platform disk optimization solution is required -- one which takes into account not only fragmentation, but coordination of I/O resources and other needed tasks as well. Utilizing such a solution, the full potential of a virtual environment is fully realized -- with maximum performance and consistent reliability.

When implementing virtual machines, make sure the underlying I/O performance issues are wholly addressed.