Feeds

Virtualisation for Beginners

It's not just for server jockeys, you know

  • alert
  • submit to reddit

HP ProLiant Gen8: Integrated lifecycle automation

Today, products like VirtualBox, Parallels Desktop and VMWare will make use of these hardware features if they're available, but still perform well on processors without them.

Parallels, for example, uses these new Intel and AMD hardware virtualisation extensions because they are almost always available on modern hardware, especially on the Mac. But Parallels can also deliver full functionality without Pacifica or Vanderpool by running in 'software mode', using techniques similar to VMWare's segment faulting

Virtualisation for Beginners

A VM is a useful testing ground for a new operating system -- in this case Google's ChromeOS under VMWare

It's tempting to think that on a multicore processor, virtualisation might allocate different cores to each of the running operating systems, but this isn't how it works. Cores are shared in much the same way as in a uniprocessor system, although the virtualiser will typically allow the user to set up 'core affinity', which associates a particular virtual machine with one or more specific cores.

But What Can I Do With It?

The most obvious use for virtualisation is running legacy apps which are perhaps no longer supported on current versions of the operating system. A tried and trusted old DOS accounting system, for example, might be carried over to Linux inside a VirtualBox virtual machine running a readily available open source version of DOS like FreeDOS.

A valuable side effect is that the application will be running in an environment isolated from other applications on the same machine, and so will probably behave more reliably than in its original habitat. And whereas in the past a failure of the application and/or the DOS environment might entail a complete reinstallation of one or both of these, now DOS and the app it's hosting can simply be reinstated as a whole, should the need arise, by restoring a snapshot of the virtual machine.

When you 'revert to snapshot' like this you'll discover immediately - or preferably have had the nous to realise well in advance - that any data used or created in connection with the application should be stored outside the virtual machine. It's usually easy enough to set up the virtual machine so that drive D: (for instance) is actually mapped to a data directory owned by the host operating system, or off on a network drive somewhere. This ensures that your set of up-to-date data hasn't been discarded with the now overwritten old version of the virtual machine.

The Power of One eBook: Top reasons to choose HP BladeSystem

More from The Register

next story
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
Apple fanbois SCREAM as update BRICKS their Macbook Airs
Ragegasm spills over as firmware upgrade kills machines
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Captain Kirk sets phaser to SLAUGHTER after trying new Facebook app
William Shatner less-than-impressed by Zuck's celebrity-only app
Do YOU work at Microsoft? Um. Are you SURE about that?
Nokia and marketing types first to get the bullet, says report
Microsoft takes on Chromebook with low-cost Windows laptops
Redmond's chief salesman: We're taking 'hard' decisions
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.