Feeds

Virtualisation for Beginners

It's not just for server jockeys, you know

  • alert
  • submit to reddit

Remote control for virtualized desktops

This is something that Windows itself has always purported to be able to do since the arrival of XP, but - in my experience at least - the success rate has been less than sterling. A VM snapshot, by contrast, is equivalent to a complete new installation on brand new hardware with a slipstream update of all your apps up to the last point of failure.

Virtualisation for Beginners

Technically, if perhaps not legally, you can run Mac OS X in a VMWare virtual machine under Windows

The Technology Behind the Magic

Virtualisation originated in IBM's big mainframes of the 1960s and 1970s when the company hit on the idea of installing a thin software layer, the 'hypervisor' immediately above the hardware that would allow multiple operating systems to run simultaneously side by side without impacting on one another or even necessarily being aware of each others presence.

'Simultaneously' needs some qualification here, because the various operating systems in fact time-shared a single CPU. But the switching would take place fast enough - several thousand times a second - to create the illusion of simultaneity.

Multi-tasking operating systems use a similar technique to run multiple apps at the same time. In this scenario, called 'context switching', only the metrics associated with each running app - the 'state' of the app - need be stored. When switching between complete guest operating systems much more data has to be saved between each switch: the total state of the guest operating system itself, as well as the states of all the apps it happens to be running at the time. Engineers call this a 'world switch'.

A Solid Proposition

The earlier Pentium processors weren't designed with virtualisation in mind. But using a software technique called 'segment faulting', developers managed to introduce world switching, and hence virtualisation to Pentium-class processors in the late 1990s. The first VMware product allowed Windows to run in a virtual machine on a Linux host, and this technology was later extended to use Windows as a host for Linux and other operating systems.

Virtualisation for Beginners

Parallels 5 for the Mac allows you to set an 'Active Corner' when in Full Screen mode

By 2006, even modest desktop processors from Intel and AMD were becoming powerful enough for virtualisation to be a solid proposition. And that, literally, is what it became. The two x86 companies each introduced hardware assistance for virtualisation into its processors: AMD-v - codenamed 'Pacifica' - and Intel's own VTx - 'Vanderpool' - were similar but different hardware virtualisation support systems.

Beginner's guide to SSL certificates

More from The Register

next story
Euro Parliament VOTES to BREAK UP GOOGLE. Er, OK then
It CANNA do it, captain.They DON'T have the POWER!
Download alert: Nearly ALL top 100 Android, iOS paid apps hacked
Attack of the Clones? Yeah, but much, much scarier – report
NSA SOURCE CODE LEAK: Information slurp tools to appear online
Now you can run your own intelligence agency
Post-Microsoft, post-PC programming: The portable REVOLUTION
Code jockeys: count up and grab your fabulous tablets
Twitter App Graph exposes smartphone spyware feature
You don't want everyone to compile app lists from your fondleware? BAD LUCK
Microsoft adds video offering to Office 365. Oh NOES, you'll need Adobe Flash
Lovely presentations... but not on your Flash-hating mobe
prev story

Whitepapers

10 ways wire data helps conquer IT complexity
IT teams can automatically detect problems across the IT environment, spot data theft, select unique pieces of transaction payloads to send to a data source, and more.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Choosing a cloud hosting partner with confidence
Download Choosing a Cloud Hosting Provider with Confidence to learn more about cloud computing - the new opportunities and new security challenges.