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.