Wednesday, June 25, 2008

Virtualization Bonus: Virtualizing Disk Drives

Well, today's subject (bonus subject mind you) is potentially a little confusing. But, here we go anyway.

The past 3 days we have talked about virtualization. We focused on vitualizing operating systems. If you don't know what I'm talking about, go back and read the posts from the last few days. Today's subject is also virtualization, however, not in the context of virtualizing whole operating systems but in the context of virtualizing a simple CD/DVD drive. So lets start with a few definitions and then get into the practical application of the glorious concept.

Virtual Drive: a virtual drive is a psuedo-drive that appears to be a CD/DVD drive on your computer. For example, when you have a virtual drive going (we will talk about how later) it appears as another disk drive in "My Computer" or Finder or whatever. The important and obvious thing here is that the drive is not real. There is no where else to put an actual CD or DVD but your existing, physical drive. Virtual drives deal with disk images, not actual disks. So what is a disk image?

Disk Image: simply, an image of a disk... wow, what a definition. Really, a disk image is like a copy of a disk (be it CD,DVD, hard disk, whatever) that is placed on your hard drive in the format of an image (i.e. ISO). Think of it as an archive (place where information is stored) of some disk.

ISO: a specific file format of a disk image. For example, all files on a computer have a specific file format. Microsoft uses .doc or .docx for Word documents, .exe for executable files (files that do something like install or run a program), etc. So, ISO (.iso) is the file format of a disk image.

Mount: a verb (to mount) related to the loading of a disk image onto a virtual drive. (used in a sentence: "I mounted the image using Daemon Tools")

Daemon Tools: a specific program (FREE) that creates virtual drives on your computer (only compatible with Windows - Mac does not need this as it is already integrated into the OS). Click here to download.

Okay, so how does this all jive together and help us out. Well, sometimes you can obtain certain programs in the form of an image. You can't just double click these images and run the program or install the software or watch the movie or whatever. You need something that will "mount" the image onto a drive. You could just burn the image to a disk (using Nero or something, although that uses an actual disk which is a waste) or you could simply use a virtual drive. Daemon Tools (previously defined) is a disk virtualization software that creates up to 4 number of virtual drives and allows you to mount disk images and run them. Just last week I downloaded a free, open source operating system. I downloaded it as a disk image and I installed it as a disk image, I didn't have to even burn it. It saved me time and effort. I love it.

Left: see the number of CD/DVD drives I have. Only one of those is an actual physical drive.

Right: You can see the same disk drives window, and also the Daemon tools on the tool tray.

Daemon Tools
is free software for Windows only. I like it more than any other one so try it out. Any virtualization software like VMware also uses virtual drives but does not require supplemental software.

I will have more in the future that will hopefully help you see the practical application of virtual drives.

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