Virtual Machines as Special class of Operating Systems

Here is a suitable definition taken from the  article published in Linux Magazine:

 "(Virtual machines) offer the ability to partition the resources of a large machine between a large number of users in such a way that those users can't interfere with one another. Each user gets a virtual machine running a separate operating system with a certain amount of resources assigned to it. Getting more memory, disks, or processors is a matter of changing a configuration, which is far easier than buying and physically installing the equivalent hardware."

Classic VM implementation is IBM's VM/CMS, but for PC users VMware has become one the most popular PC-based implementation and it allo7ws you to run other operating systems like MS-Windows on your linux desktop. Rado has written a short review about this PC emulator for those who still did not check out the free demo.

News

VMware, NSA working to protect classified data
IDG.net VMware and the U.S. National Security Agency have teamed to research and develop new technology that they say could make it easier and less expensive to protect highly classified information.

NewsForge GPL Linux virtual machines and virtual machine clustering

LinuxTicker - Feature Emulating a complete PC with VMware

VMware has become famous since it allows you to run other operating systems like MS-Windows on your linux desktop. Rado has written a short review about this PC emulator for those who still did not check out the free demo. Also he has interviewed Reza Malekzadeh, the director of marketing at VMware.

linux.oreillynet.com Interview Mendel Rosenblum of VMware [Feb. 18, 2000]

David Sims: How is that handled? Is the virtual machine an application that's running these operating systems?

Rosenblum: Well, we have sort of a unique architecture where we're both an application and what is technically referred to as a virtual machine monitor which is like a special type of operating system. So, when we run one of the additional operating systems you add to your machine, we're actually running in the most privileged mode of the processor and have control of all the hardware on the machine. So, in that sense, you know, we're an operating system that just happens to allow other operating systems to run on top of them. So, we also have a mode in which we run in which we appear to the user as just a normal application running on one of the operating systems. That makes it a lot easier for the user to interact and makes it a lot easier to install and configure us. You download our product on say NT and it installs like using an install shield like any other application. So, the answer is we're kind of both, an application and an operating system.

Sims: I think the analogy that more people have heard of VMWare or would be familiar with would be running PC applications, something like PC soft on the Macintosh.

Rosenblum: Right.

Sims: Is it similar technology?

Rosenblum: Well it appears similar in that you can have it appear like an application that runs a PC application and PC operating system, but the technology is actually very different.

Because we're running on the same like Intel x86 hardware, we can actually directly use the hardware to run the PC software like the operating system applications. And so what our software actually does is actually takes the hardware and uses it to run in these additional operating systems directly. So, unlike the sort of emulation technology like Virtual PC and the stuff that has come up on the Mac, we're not really a simulator and we don't really have the kind of slowdowns you experience when you're running through all these simulation layers, since literally what we're doing is just sort of giving the hardware directly to the operating system and having it run it.

Sims: You know, it's interesting that you mention the slowdown. I have heard that it takes quite a bit of memory to VMWare. Is that your feedback also? How much memory do you recommend on, say a Linux running on a Pentium box?

Rosenblum: Well, I think the minimum memory you would even probably consider doing this is 64 megs and it runs very comfortably in a 128 megs. So we recommend is put as much memory as you can on your machine, but we have people write us all the time saying "I'm running with 64 megs and it's enough." The issue is that, you know, you're running this whole new environment with the applications. It will still run if you don't have the memory, enough physical memory on your machine, it's just that you end up having to go to disk and that can slow you down tremendously. The minimum requirements to actually run the software is even lower than 64 megs it's just that end-user experience, your disk light would be on most of the time, you'd be sitting there waiting for the disk.

[Oct 1, 2001] Novell tows VMware into education market - Tech News - CNET.com

[June 22, 2001] Connectix has announced the release of a beta version of its Virtual PC product for Intel hardware. The software allows users to run guest operating systems, much like VMWare. Unlike VMWare, however, the product only runs under Windows 2000, Windows NT, and Windows ME. According to the company, the final product will ship in mid-June at an estimated price of $199.

PCWorld.com wrote up a brief review of the product, giving it generally good marks, but pointing out the underlying irony of running a stable operating system as a guest under Windows:

Red Hat Linux installed and ran smoothly. However, the stability benefits gained with Linux are negated by fact it runs under the less-stable Windows 98. Besides supporting Red Hat Linux, Virtual PC works with the latest Linux distributions from SuSE and Mandrake.

The no-cost download is available at http://preview.connectix.com/

LINE Is Not an Emulator

LINE Is Not an Emulator. LINE is a utility which executes unmodified Linux applications on Windows by intercepting Linux system calls. The Linux applications themselves are not emulated. They run directly on the CPU just like all other Windows applications.

Click here for a list of applications that are known to work (at least partially) under LINE.

LINE was created by Michael Vines

BSD Today Running numerous operating systems at the same time

InfoWorld: Am I the only one who doesn't know why to use VMware?(Dec 10, 2000)
LinuxPlanet: VMware Makes Move for Server with Two New Products(Dec 05, 2000)
NewsForge: Plex86, VMware compete to get rid of dual booting(Nov 20, 2000)
plex86.org: Plex86 runs Windows95(Nov 16, 2000)
Linux-Mandrake.com: MandrakeSoft buys Bochs for Linux and commits it to Open Source.(Mar 23, 2000)

[Sep 30, 2000] Inside VMware

VMware enables you to run a Virtual Machine, which is VMware's version of an emulated state of Windows, Linux, or FreeBSD. You heard me right-on VMware, not only can you do Windows, but also Linux and FreeBSD. That means if you need to test out that new version of Linux, but you don't want to format your drive just to test it out, VMware can just create a virtual drive and you're on your way to seeing what the latest version of your favorite distribution has to offer.

To date, VMware has been pretty much a development product, but thanks to demand for a stable, versatile operating environment, VMware has upped the ante and created their best version of VMware yet-2.0.2.

If you've used a package like Connectix VirtualPC for the Macintosh PowerPC, you'll notice many likenesses it shares with VMware. The website may really hype VMware up and make it sound like there is no loss of performance, but the simple fact is that you do lose clock speed, RAM and hard disk speed, just like you would with any piece of emulation software.

In fact, you can tell both VMware and VirtualPC are designed along the same lines. The configuration is much the same, except one is obviously more PC-fied, while one is more Mac-centric.

Although, what it comes down to is compatibility. VMware does a much better job at emulating x86 hardware, probably since it's operating on top of x86 hardware. That's a logical assumption, right? Enough with guesswork, let's take a look at what's really going on.

Here we see how it really works. A typical PC works like we see on the left. I think the diagram oversimplifies things in a way, but it will do the job.

Essentially, VMware interfaces directly with most your system hardware, which is one way it achieves pretty good performance even on low-end machines. Don't get me wrong, you still won't get the full speed of your PC out of VMware, this happens because things like the hard disk access (where it looks to be hurting the most) are still done through the operating system.

This is how it all happens. This diagram shows you the devices which need VMware still needs to call through the OS-disk, memory and CPU.

Once again, VMware has a few tricks up its sleeve. One great thing about VMware is that you can utilize your local network to get access to your Windows or Linux filesystem. In fact, you can even use a regular network along with your local network at the same time, so you don't need to sacrifice anything with the networking setup.

NewsAlert - Story Dell Leads $20 Million Strategic Investment Round in VMware

PALO ALTO, Calif., May 24 /PRNewswire/ -- VMware, Inc., the leading provider of application and service delivery platforms based on innovative virtual machine technology, today announced the closing of a $20 million strategic financing round led by Dell.

VMware launched its first product in May 1999 -- software for desktop personal computers that enables a single PC to simultaneously run multiple, protected sessions with any combination of Linux, Windows NT, Windows 2000 and other Intel based operating systems. Today, VMware has more than 385,000 registered users, and is licensed in 5,000 corporations, in more than 100 countries. The company will use the funds to accelerate the development and deployment of server-based products for providers of hosted applications and services over the Internet or corporate intranets.

"We see VMware as a significant emerging technology in the computing industry," said Jim Totton, Dell's vice president of worldwide software development. "Dell continues to invest in technologies that show strategic potential in the marketplace."

"This financing positions VMware to move into the next phase of growth and evolution of our business strategy: deploying VMware virtual machine technology as a platform for Internet commerce and infrastructure," said Diane Greene, a co-founder and chief executive officer of VMware. "We expect the investment to have a huge impact on our current desktop business as well as speeding time to market for our server products."

VMware's server products will address some of the most critical issues facing providers of hosted applications and services. These include how to guarantee security on shared servers, maintain the stability of existing servers when adding new applications and services and overcome the incompatibility of Linux, Windows NT and Windows 2000. "Today's solution -- a server for each application, service or customer -- is not only expensive, but creates enormous systems administration and management problems," said Greene.

VMware

http://www.VMware.com/

Linux Today - CNET News.com VMware ready to capitalize on hot server market

PRNewswire: VMware Announces VMware Express for Linux(May 09, 2000)

ZDNet: VMware Welcomes Guest OSes(May 02, 2000)

LinuxPlanet: VMware 2.0: Virtually Magnificent(Apr 10, 2000)

PRNewswire: VMware Signs OEM Agreement With Microsoft(Mar 29, 2000)

osOpinion: Somebody give VMWare some venture capital. Quickly!(Mar 22, 2000)

PRNewswire: Google Deploys VMware Software(Mar 13, 2000)

"Google also uses VMware to access both the Linux and Windows applications they need. According to Google co-founder and president, Sergey Brin, "Working at a hot Internet start-up today, access to both Linux and Windows is a must, since there are hundreds of great applications and tools for both. VMware lets me use both Windows and Linux on one computer at the same time.""

O'Reilly Network: Interview : Mendel Rosenblum of VMware(Feb 27, 2000)

PC Week: VMware updates software for running multiple OSes(Feb 17, 2000)

The Standard: Why Choose [when VMWare Lets You Switch]?(Feb 08, 2000)

LinuxTicker: Emulating a complete PC with VMware(Jan 24, 2000)

"VMware is not just an emulator. It is complete virtual machine "built" on the underlying layer of hardware and the existing operating system. It doesn't take control of your keyboard, mouse and video -- you can run it in full screen mode as well as in a window. This, however, requires some modifications to get everything to act as usual. The virtual machine runs on top of the existing OS, using its devices to access the underlying hardware. The great advantage of this is that you can, for example, have up to four virtual network adapters on your virtual machine, and have them all bound to the network which uses the hosting OS as gateway."

Q: What is your target market for the product?

A: There are many market targets that we find suitable for VMware: people who need Windows Productivity Applications on Linux (Office, Mail, Browsers) because they can run Windows programs without the need to reboot the computer; developers who write and test software as well as people who provide tech support, because they can have multiple platforms to work on and test various configurations at the same time; people who develop web content and web sites, because they can use different browsers on different platforms to preview the content they're working on.

Q: Do you believe your product will change the way people think about operating systems?

A: Yes, we would like to think that VMware will change the way people think about their PC and operating system. Today, there is a 1 to 1 mapping between your hardware, the OS you run and the applications you can run: For example, on a PC running a Windows Operating System, you can run only Windows NT and/or Windows 9x compatible applications, on a Linux PC you can run only Linux compatible applications, etc. And there's no way to concurrently run applications for Windows NT and Linux on the same PC, natively.

As a result, you are limited in what you can do:

• Software testing, installs, and upgrades are onerous
• Operating system or application crash have a high impact and bring down the PC
• There is a limit in the applications you can run

These are basically arbitrary rules preventing innovation.

With VMware, you can now do much more:

• Install software or test upgrades in a safe environment without impact on your working world.
• A crash within a Virtual Machine is limited to that environment and will not affect the rest of the PC.
• Run the applications you need, regardless of the OS requirement

Q: Do you plan to port VMware on other platforms?

A: Not at this point. VMware technology is tightly linked to the Intel x86 Architecture.

Q: After unveiling some secrets about Transmeta CPU, do you think that VMware and Transmeta share some points of view? If you were making decision to choose best things from virtual machines philosophy and new CPU "idea", what are the things you would take from both worlds?

A: It is a little too early for us to speak on that subject. Transmeta has not completely unveiled their technology at this point. We are anxious to see the Crusoe launch on January 19.

Q: How would you compare Bochs and Wine projects with VMware?

A: Wine allows some unmodified Windows 3.1, Windows 9x and Windows NT binaries to run on Intel PCs under Linux and other x86 UNIX-like operating systems. Wine is an implementation of the Windows 3.x and Win32 APIs on top of X and Unix. One advantage of Wine is that it does not require a separate Microsoft operating system to run applications. Wine also provides relatively good performance as application code runs natively on the underlying hardware. Individual Windows applications may or may not be supported by Wine. Wine is an alternative implementation of the Win32 API while VMware is a virtual machine monitor. VMware allows multiple operating systems to run by multiplexing them onto the underlying hardware. VMware requires a Microsoft operating system to run Windows applications and provides very high levels of application compatibility. VMware also provides advanced capabilities such as isolation and encapsulation that Wine does not provide.

Bochs is an emulator: Bochs runs entirely at user level and emulates all of the different devices and CPU instructions. As I stated before, VMware is a Virtual Machine monitor (not an emulator or simulator) and as such will take advantage of the underlying hardware to execute instructions and have much better performance. Also, Bochs is not feature complete at this point. Last I checked, networking and some other features where not complete.

Q: How secure is VMware? I.e. is it possible to break in from the cracked virtual box into the real operating system? (from the Internet and from the local machine, if we imagine that user can't run anything other than virtual machine)

A: The Virtual Machine is like another computer on the same network. If you have the Virtual Machine "VM1" running on top of the host "H1", it is like having two machines, VM1 and H1 on the same LAN. As such, any security violation that can be done between two machines on the same LAN can be done between VM1 and H1 (through networking protocols). From VMware's perspective, the memory and disk are completed isolated. One cannot get to read, and/or corrupt data on H1 through the VM1. If you decide to not have networking on VM1 (disable the Ethernet interface through the settings panel), it will be 100% isolated from the rest of the world (no network access to it). There is a variety of other networking settings that you could apply to VM1 and H1: attach H1 to VM1 through a VPN (Virtual Private Network) and VM1 to the world on the Internet, set one up as a firewall and use IP masquerading for the other one, etc. You can therefore do much more with a PC when using VMware :-)

Q: Could it be possible that some exciting new Microsoft technology (like DirectX 15.0 ;-) ) suddenly prevent VMware from running applications that use it? How long would it take to release new version, the one that support that new feature?

A: If there is a new technology not supported by VMware, applications using it would either not run or run in a "less complete" mode. Depending on the technology, the effort to support it will vary in difficulty. Our goal is to be feature complete and we are working in that direction. We are of course very involved with the evolution of technology and do our best to stay on top of it :-)

Q: If there's one thing you would like to improve in VMware, what would it be?

A: We are always working on improving our software. As the product matures, we are trying to better understand how to serve our customers better. We have a pretty steady stream of communication with our users through Email, and newsgroup postings. Each of our releases have addressed bug fixes and product enhancements as demanded by our users. In the long run, we would like to be as feature complete as possible and support a large variety of host and guest operating systems.

Q: What are your future plans?

A: We would like to build a solid company and expand our product line and technology to help change the way people use their PCs. VMware wants to help people go beyond the current constraints of the traditional computing model. VMware delivers flexible computing to dramatically increase productivity and innovation. Our current product is aimed at the desktop market. We will look in ways our technology could be used in other fields.
 

Linux Forum

I'm not saying that Linux can't do everything I want. It just doesn't do it the way I'm used to. Since I come from the world of Windows desktops, there are some things I've gotten used to and don't want to leave just yet. It's not that Windows does them better, faster or more reliably; it just does them in a familiar way. As the Linux Desktop environment continues to evolve many of these programs will be either ported or similar programs will have duplicate feature sets. Until that blissful day, there is VMware.

VMware is a virtual machine emulator. It doesn't emulate any particular Operating System. It emulates the machine, and it is up to you to install the OS. In my case I need Windows 98 to run several programs that I don't have an equal for under Linux. Below I'll give you my install experiences and tell you what I've found to be good and bad about the product. One thing you should to keep in mind, I generally don't read the documentation first. There is no challenge in software with documentation. Beside installation and operation should be intuitive.

	The machine I used for this install is:
	Celeron 300A
	128MB SDRAM
	Creative Labs AGP Banshee Video
	Adaptech 2940UW SCSI Controller
	(2) 4GB SCSI Drives
	Panasonic 16X CD ROM
	ESS chip sound card
	Realtek Ethernet card

As you can see from the list of components, this is a slap together machine. I'm running stock Mandrake 6.0 with updates from one of their mirrors. This machine is configured as a desktop with no server type services other than Samba. I have recompiled the kernel like any good user should to optimize it for my machine components.

I downloaded the demo from http://www.vmware.com/ and registered for the free 30-day trial. Installation was quite easy. In fact I really can't remember anything siginificant about the installation process. When I first ran the program and ran through the configuration I realized that I needed about a gigabyte of free space to create the virtual drive. You can set this to any size you want and tailor it to the OS you are going to install. This gave me reason to add the 2nd 4GB drive. After the configuration file and virtual drive was created. I proceeded with the install of Windows 98. The virtual machine comes rather complete. Below is a snapshot of the initial boot process. You can even go into the virtual BIOS. The install of Windows 98 ran flawlessly. The only thing to note is the install took about twice as long as it would have on a stand-alone machine. I feel this is due to the CD ROM access, more about this later.

 

VMware boot's like a real machine complete with memory checks and BIOS.

Once the Windows 98 install was complete the virtual machine rebooted, into Windows 98 with no sound and a 16 color screen. Each time the virtual machine reboots, Linux stays up and the window reboots. This makes the Windows desire to reboot after every little change more bearable. At this point I downloaded the VMware Tools and installed that into Windows 98. After a reboot I had the same color depth as my X window (32 bit) environment and no sound. Two and a half hours of trying to figure out what was wrong with the sound (remember not using any documentation), I finally found how to enable sound support in the configuration wizard and got Windows 98 to detect the virtual sound card. I had sound after a Windows reboot.

From that point on it has worked like a charm. My Linux machine hasn't rebooted in the past eight days even though Windows 98 reboots at least three times a day. Every desktop style application I've installed has worked flawlessly with no noticeable delays in operation. I have even installed a few games. Games usually require a bit of adjustments in presetting the screen size and color depth. To do this you will have to set your screen depth on your X Window environment since the virtual machine runs at the same screen depth of your X Window environment.

Below is my list of neat stuff, things to watch out for and what needs to be fixed either by VMware in upcoming versions or through a workaround.

Neat Stuff

You don't have to mount floppies or CDs. VMware takes care of the mount process. It appears that VMware doesn't really mount the CD or floppy in a traditional way. It just accesses the device as needed. This could be one reason for some of the apparent slowness during installs.

While the applications are running and not accessing an external device, there is no apparent slowness. I've put a heavy processing load on my Linux machine and popped over to VMware. The switch to the virtual machine is slow but once I'm in the virtual machine everything appears to run at normal speed.

You can make multiple virtual machines. You can even duplicate a current configuration and virtual drive and run the duplicate as if it was a new machine. If you are really paranoid you could setup a script to automatically copy your working virtual desktop every night so if Windows blows up on you, you have a complete backup.

Using Samba you can mount Linux directories as virtual drives. This way you can keep your virtual drive fairly small and share your data files between Linux and your virtual machine. If you are curious how to setup Samba for this you can check out Simon Says Simple Samba Server for setting up a simple Samba server.

Watch Out

Windows has a really neat feature of polling the CD at regular intervals for auto notification and running all of those autorun files on the CDs. Turn it off. This is the first source of slow downs you will find on your virtual machine. To turn it off open your Windows Control Panel, open System, go to Devices and open the properties on your CD Rom drive. Uncheck Auto notification.

You should have at least 128MB of RAM on your system if you plan to run Windows in your virtual machine. Linux runs quite well in 64MB and Windows needs at least 64MB for any sort of reasonable speed.

Make sure you install the VMware Tools. This greatly speeds up your screen displays. VMware also offers an optimized version of XFree86 3.3.3.1. I haven't installed this because I'm using a 3dfx video card and I'm currently using a specially patched XFree86 3.3.3.3.

When you install the network ability you have several options. The one I chose is bridged. Inside Windows 98 I had to assign a unique IP address to my virtual machine. In many ways I feel that this is the best approach, at least for my networking environment. This makes the virtual machine very independent. It looks and acts like another machine on the network.

Bleah - Things that need to be fixed

There is no ability to change the color depth of the virtual machine's screen without changing the depth of the X Window environment. Many games and education software run at 256 colors. My Linux desktop doesn't look that great in 256 colors.

VMware needs to use lots of space in /tmp. For most people this won't be a problem, but for me I only have 40MB free in that partition. When it fills up, the only way to fix it is to crash your virtual machine. This was bothering me so much I went to the VMware web site and read the documentation. There is a workaround where you can set the temp directory to another directory by adding a line to your .cfg file for your virtual machine. This fixed the problem for me, but I really would have liked for this to be an option in the configuration wizard. To date I haven't seen it take too much more than 50MB for temp space.

All in all this is a great program. It allows me to run programs like Quicken, Eudora, Turbo Tax, Bryce 3 and Starcraft on my Linux machine without dual booting. I've always disliked the way MetaCreations programs took over the whole screen. Now, I can have it take over a whole virtual machine and keep that machine in a window. If I had to rate vmware I'd give it 4 1/2 bears out of 5. But we don't do ratings like that here... yet.