server

In past blogs, I’ve discussed some of the big-picture benefits for server virtualization. This week, I wanted to give some thought to the concept of desktop virtualization. Of the two technologies, the desktop variety has been much slower to take off in the marketplace, and frankly, there are some good reasons for that.

In both cases, the fundamental underlying technology operates on the same basic principle: By uncoupling the operating system and application software layers from the binary code layer that actually operates the chip-level hardware, you can accomplish some cool things. Perhaps the number one benefit is being able to create the illusion of multiple independent physical machines (AKA “virtual” machines) all living side by side on a single hardware platform. These virtual machines can lead diverse and independent lives, being dedicated to various tasks and even running on different operating systems.

The benefits at the server level are almost self evident. For one thing, running multiple virtual machines on a single box can be more efficient, because you can eliminate underutilized machines. As a result, you can reduce hardware costs, eliminate redundancy, and slash you electric bill. Support and maintenance costs can also be reduced, as you consolidate your data center. Read More »

Virtualization is one of the oldest and most fundamental concepts in computer science and IT; if you look carefully, it is almost everywhere – desktops, notebooks, servers, SANs, cell phones, even GPUs!

Virtualization entails replacing a dedicated computing or storage resource (e.g. CPUs) in a system with an abstraction of that resource (e.g. a virtual CPU) that appears to be dedicated, but is actually shared between several uses and managed to achieve higher efficiency. The appearance of being dedicated (i.e. isolation) is key because dedicated resources are very easy and convenient to use; there’s no concern that someone else might be hogging that resource.

This sounds deceptively simple, but the reality is quite complex. Many times, different elements of a system will conflict with one another – those conflicts must be seamlessly arbitrated. Even if this is done correctly, sometimes the performance overhead is so bad that the result is almost unworkable.

Virtual memory is a particularly relevant example. To virtualize memory, there are two key issues – resources and how to access them. Typically virtual memory is broken down into two sections – kernel space, which is a private region of memory for ring 0 (i.e. the most privileged) software – that is the OS kernel, IO devices, drivers and a few other odds and ends. Kernel space cannot be paged out to disk, so there are no page faults in the kernel. This restriction is one reason why most kernels are small. User space is made available to ring 3 software (aka applications, the least privileged) and can be paged out. The OS provides and a separate user space for each application, which is how they are protected from each other – so that bad data in one application will not cause problems elsewhere, and that applications cannot maliciously or accidentally access each other’s data. Read More »

Could virtualizing your company’s servers actually be part of your patriotic duty? It may seem a little far-fetched at first glance, but let’s take a deeper look at national trends and the important take-aways from recent national political campaigns that drew a bead on our country’s most pressing problems: a teetering economy, our alarming dependence on foreign oil, and a growing need to address environmental concerns such as global warming.

Is there something IT professionals can do that has the potential of addressing this triple threat of social, economic and environmental ills? The answer could be virtualization. Proven technologies that allow a single server to take on a variety of unrelated tasks that would normally require the use of multiple dedicated servers offer some obvious benefits in the areas of cost savings and efficiency. Can those benefits also translate into improved fiscal performance, reduced consumption of energy resources and a lower carbon footprint? The consensus seems to be in the affirmative. Read More »