An Overview of Virtualization

IndioMan writes to point us to an overview of virtualization — its history, an analysis of the techniques used over the years, and a survey of Linux virtualization projects. From the article: "Virtualization is the new big thing, if 'new' can include something over four decades old. It has been used historically in a number of contexts, but a primary focus now is in the virtualization of servers and operating systems. Much like Linux, virtualization provides many options for performance, portability, and flexibility."

Comments

Apple

[99BottlesOfBeerInMyF]

This article is an okay overview of many of ways virtualization is now being used. As an aside, has anyone else noticed Apple seems to be missing the boat this time? They're certainly benefitting from virtualization with several players in the market providing emulation solutions and tools now that they are on Intel, but Apple themselves seem to have done nothing and not even provided a strategy. Servers are moving to more virtual servers on one real machine, but OS X's license forbids it from fulfilling that role. Tools for using OS X as a thin client for accessing remote virtual machines are likewise weak. Apple hasn't even provided a virtual machine for their customers to emulate old macs so that users can run OS 9 apps on the new intel machines and they restrict redistribution of their ROM files to make 3rd parties unable to do this. No mention of adding VM technology to OS X has been heard, despite its inclusion in the Linux kernel among others.

Does Apple have something against VM technology? Are they simply behind the times and failing to see the potential?

Re:Apple

[99BottlesOfBeerInMyF]

Virtualization is usless in a desktop multimedia user environment. Video cards, sound cards and the like are bus mastering devices and you cannot virtualize hardware access unless you own the whole environment. In simple terms, virtualization is only usefull in the server arena and useless on the desktop.

As someone with two VMs running on my OS X laptop right now, I'd have to disagree with you. As for sound cards and video cards the sound works just fine and at least two companies I know of are working on support for allowing hosted OS's full access to video card acceleration.

Re:Apple

[diamondsw]

Let's see, why don't they do virtualization...

• They don't want you to use OS X in a VM, as it makes it trivial to use it on generic PC's, which eliminates the vast majority of their revenue.
  
• They don't include virtualization software themselves as Parallels and VMWare are doing a good job if you need such a thing, and they don't want to alienate them.
  
• And not strictly virtualization, but you mentioned it - they don't want to make it easy to use OS 9. It's been dead to them for years (and porting Classic to Intel would not have been easy, given the way Rosetta works). Meanwhile, they do nothing to hinder or help SheepShaver and others; the ROM files needed are available from Apple's website (although not easy to find).

None of this is hard to figure out. Yes, there are reasons it would be nice, but it's pretty obvious why they're not too keen on it.

another reason why virtualization is so hot

[anomalous cohort]

I work at a small ISV which just bought SourceForge, Enterprise Edition which is an Apache/JBOSS/PostgreSql/CentOS app for managing SDLC. For a company of our size, they package this as a VMWare image. Installation is incredibly easy. I can definitely see how free virtualization can be a big boon to companies selling and/or consuming web applications for small deployments.

Re:QEMU

[julesh]

I'm not sure why you felt the need to mention QEMU specifically.

I suspect because the article incorrectly describes it as an emulator, while it is capable of full virtualization if the plugin the GP post linked to is used.

It's not the only such mistake in the article: Xen is described as performing paravirtualization, but it too is capable of full virtualization in some cases (i.e., when it is supported by the hardware).

Re:Thanks, IndioMan & kdawson

[moco]

Since I'm not a server admin, I've always wondered about the use and importance of this "virtualization" I've been hearing so much about .

For the home user virtualization can be used as a separate PC to surf the net without fear of malware, when you are done surfing just restore the VM to the "clean" state, think "your pr0n browsing PC". You can also use it to test software before contaminating your host PC with stuff you decide not to keep. I visualize it as a sandbox to play in before messing up with the "real" system.

Check the vmware player appliances, there are lots of good ideas there, many of them are for business use but there are several that can be used at home.

For the developer / tester virtualization provides a set of target operating systems to test / debug the software on without need of having the actual physical hardware.

Of course, in the data center it is the next big thing, too many advantages to list here.

Re:*Another* Layer?

[QuantumRiff]

For us, the nicest thing about virtualization is the disaster recovery. If our building burns down, we can quite literally get any PC we can find with a ton of RAM, load Virtual Server, and load the hosts right back up. Much, much faster than going and configuring all the weird drivers and raid cards, partitions, etc on a normal non-virtualized system. On the same note, if one of my servers goes down, I can quickly load up the VM on another box, which means I can take all the time in the world to get the original server back up, so I don't have to worry about the really expensive "4-hour" support plans, but the much cheaper "next-day" support plans. I also keep a VM copy of our web server handy. (Web server isn't on a VM, yet, because of the speed issues), so that when I need to take down the real, faster, web server, I change one DNS setting, and all my users notice is that the web is running a little slower...

Re:3d?

[Ash-Fox]

But they all have one major showstopper of a problem: I can't use accelerated 3D on the latest graphics cards under virtualized OSs.

In Vmware:

Edit your .vmx file.

Add the following:
mks.enable3d = TRUE {- Requires acceleration on the host, because it passes things directly from the guest.
svga.vramSize = 67108864 {- This line increases the vram size, you might want to customize it.
vmmouse.present = FALSE {- This disables the 'absolute' pointing device in the guest OS (as applications that require directinput relative mode needs to turn off 'relative' mode in the guest). Note: If you unset this option, you should also turn off the preference for motion ungrabbing in the settings dialog

Unfortunately not all aspects of 3D acceleration on the guest are actually accelerated -- Which are some of the following:

• Hardware bump-mapping, environment mapping
• Pixel & vertex shaders
• Textures with one, three, or four dimensions
• Multi-vertex streams
• Projected textures