One especially important thing to keep in mind is that the virtual hard drives used within your virtual machines are stored as single physical disk files on your real hard drive. Under Virtual PC these have file extension .vhd and under VMWare they use .vmdk.
It’s important to safeguard these files. A corruption on a real hard disk may damage some files but the computer may continue to operate and the data may be recoverable. Unfortunately, though, a corruption which damages the virtual hard drive doesn’t just hurt part of it but all of it. If the virtual hard drive file cannot be opened because it is damaged then it cannot be used at all and your whole virtual computer is gone.
Therefore, it is vitally important to establish a backup regime for your virtual hard drives. This does have big payoffs and is worth the effort. For one thing, it becomes a no brainer to remove undesirable changes you have made by merely restoring a backed up virtual hard drive. You could fire up your virtual computer and then try out some new software which you decide you don’t like. While it may be possible to uninstall the software, you can simply revert back to a previous virtual hard drive which effectively means the software install just never happened. There’s no fear of leaving files lying about or system changes which aren’t cleaned up by the uninstallation.
In fact, you could completely trash your virtual PC and resurrect it within seconds by restoring a virtual hard drive backup. If you recognise this then the backup regime does not become burdensome but instead a tool in your arsenal, allowing you to explore and make changes with full confidence you can wipe out anything and go right back to your starting point. Or, you can pass on your virtual hard drives to other people. You can configure a virtual computer exactly as you wish it to operate and give it to another person knowing with full confidence when they load it into their virtual environment it will be exactly as you left it. There are no concerns about running on different hardware platforms whatsoever.
Virtual hard drives can be copied to removable storage like a portable USB hard disk. This allows you to produce an entire library of different virtual machine environments – with different Linux distributions, different configurations, perhaps even two separate virtual computers running Ubuntu and Kubuntu. Armed with nothing more than a laptop running VMWare you have an entire repertoire of systems at your beck and call. Your portable hard drive won’t be just lugging data around but entire servers!
Virtualisation is definitely a technology that is being developed and improved rapidly. It is becoming mainstream and will, I believe, be a viable software distribution method in the future. What we’ve covered here today is straightforward and simple and will help you on your journey to embracing virtualisation on your own systems.
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David has been computing since 1984 where he instantly gravitated to the family Commodore 64. He completed a Bachelor of Computer Science degree from 1990 to 1992, commencing full-time employment as a systems analyst at the end of that year. Within two years, he returned to his alma mater, the University of Newcastle, as a UNIX systems manager. This was a crucial time for UNIX at the University with the advent of the World-Wide-Web and the decline of VMS. David moved on to a brief stint in consulting, before returning to the University as IT Manager in 1998. In 2001, he joined an international software company as Asia-Pacific troubleshooter, specialising in AIX, HP/UX, Solaris and database systems. Settling down in Newcastle, David then found niche roles delivering hard-core tech to the recruitment industry and presently is the Chief Information Officer for a national resources company where he particularly specialises in mergers and acquisitions and enterprise applications.