Slashdot Mirror
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."
Just wanted to point out that qemu can also do virtualisation on Linux, just like Vmware, with a closed-source kernel module. It works quite well too. http://fabrice.bellard.free.fr/qemu/qemu-accel.htm l
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.
MOL is a true work of genius. Even on pretty old PPC hardware it functions with almost no slowdown. (Linux host, OS X and Linux clients). Compared to contemporaries it had no equal - the current generation of products on x86 are just starting to catch up. I'm most impressed with the way my powerbook can sleep (close the lid) under Linux and all of the hosted sessions quietly pause themselves with no problems. They even resume a network connection perfectly on waking up.
It'm glad to see similar happening on x86, finally, as it's one of the things that really made PPC based machines special. (There is some documentation for MOL and Kubuntu here.)
Think of the Children; Sleep with your Sister
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.
moi
and had serious issues with stability and networking. I detailed my experience at my blog if anyone is interested. I also tried using the Linux version of Parallels and had similar issues. If anyone has gotten Vista to run under Xen I would be very interested in your feedback
You'll probably never see this comment, but so be it...
Where we've found it incredibly useful is in 3 cases:
1) Any server where end users may cause damage. In our case, we have a remote desktop available to the end users via Citrix. Yes, it's secured -- but there's always SOME chance that an end user will mess it up somehow. By running the Citrix server in a virtualized non-persistant environment, any damage can be corrected by simply rebooting the virtual Citrix box.
2) Very low utilization applications that are required to be on their own server for support purposes. There's tons of Windows financial & business apps that won't play nice together, or are simply unsupported by the vendors if there's anything else on the box. The easy solution is to simply load these lightly used images on a single host box.
3) Migrating services. If an app is installed in a virtual environment, and the user population suddenly triples, all you have to do is migrate the virtual image to heavier duty host hardware.
Performance is incredible, there's no comparison, for example, with VMWare running fully-virtualized Windows, which is way slower than hardware-virt (nowadays maybe that VMWare allows to use VT-x/AMD-V?
VMware has supported VT/Pacifica from the begining. The other statement about hardware virtualization being fast now (without MMU support) is not true. That is the reason VMware recomends using software virtualization even on products that has full support for VT/Pacifica.
Well, in the server space, virtualization gives you immense flexibility, thanks to simplified backup and restore, migration, failover, and so forth, not to mention enhanced security and auditability. Yes, you could implement those features for every service you run, but why go through that effort when it's more easily done with a virtualized environment?
For developers, VMs are fantastic. Not only does it let you target multiple architectures easily, it also makes it possible to create, backup, restore, and teardown machines quickly, which is damn handy for certain modes of development (being able to revert to a known-good configuration of a test system is *very* useful).
But you're right, on the desktop, the uses are limited, probably to security, where you can easily sandbox legacy software.
Sure Steve, Virtualization isn't a panacea, and you've cited some of the places where it doesn't fit.
However the more common example by far in the enterprise is the deployment of a fairly small app that consumes a fraction (say ~10 pct) of a server's worth of CPU capacity. For all sorts of reasons, including ownership and independence, these tend to run on their own dedicated server.
Real cool example? Let's start with your scenario, a small ISP with a web server, mail server, and DNS server. To avoid the single point of failure, deploy all three applications across an active/standby or active/active clustered pair of physical servers, with some kind of shared-storage. Run each server (web, mail, and DNS) in its own virtual OS. Net benefit: Increased uptime _and_ reduced physical resources.
Another real cool example: How about security. Increasingly, expect to see security best practices mandate running applications within a virtual OS. For a good example of this, check out this PDF from Sun. Yes, it is Solaris specific, but expect other OS / Virtualization combos to move in this direction in the future.
Edit your
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:
Change is certain; progress is not obligatory.
The games I've seen VMware running myself... The sims, World of Warcraft, Half life and Second life.
Change is certain; progress is not obligatory.