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Đây là bài so sánh gần đây về VMware 5 và Virtual PC 2004 ...   Virtual PC 2004 vs. VMWare Workstation 5 July 11, 2005 By Jeanne Paschang ( http://www.adminprep.com/articles/default.asp?action=show&articleid=81 ) Introduction Test, test, test. How often do we hear this mantra? As system administrators and engineers, we probably hear it all the time. Below are just a few of the situations you most commonly encounter regarding testing. • “Before you install this service pack, be sure to test it.” • “Before you restore your SQL server, test the process so you know what to expect.” • “Before you do an in-place upgrade of your Exchange server from Exchange 2000 to Exchange 2003, make sure you test it first.” It is always good advice to test programs and procedures before implementing them. It is also a good practice to back up any systems undergoing a significant change. But what is the best way to do all that recommended testing? Obviously, the best way to perform testing is to install a test lab that is as close as possible to the real environment. Why test and who has time? I worked as a full-time network administrator over the last fifteen years for several different companies. I was one of those paranoid system administrators as many of us are. Downtime to the company meant lost revenue. To me, downtime meant angry users, lost time and/or a lost job! As a result, service packs, new product installations and upgrades made me nervous. After all, these companies relied heavily on their information systems. A bad patch could mean disaster. Some people dream of new houses, cars or boats. I often dreamt of a test lab. To that end, I presented several business cases for building a test lab. The reaction was always the same: “you want us to dedicate equipment to sit around and do nothing most of the time?” Even when I presented how many dollars could be lost in terms of productivity as the result of just a single bad software or procedure, they just did not seem to get it. One of the companies I worked for even wanted to get into the business of installing networks for small businesses, yet they resisted the idea of a test lab. Today, as a technology instructor and consultant, I usually ask my corporate students if they have a test lab environment. The response I often get is peals of laughter. Many of them respond as follows. “Of course we have a test lab. We call it our production environment!” If they do have a lab, it consists of whatever junk machines they could piece together. I would say only about one person in eight ever raises their hand and says they have a dedicated test lab. I can understand the resistance five or ten years ago when an extra PC was a big dollar item. Additional space is often the other consideration, particularly in areas where real estate is at a premium. Time constraints are the other problem. A test lab requires regular care and feeding in terms of loading and re-loading operating systems and applications. Even today, the test lab appears to be a poor relation to the rest of the IT world. Virtual Machines to the Rescue But no more! Now we have some excellent products at our disposal to test whatever we need to with far more ease than in the past. Many administrators discovered the advantages of virtual machine products many years ago. Yet, I am surprised at how many administrators I encounter who are not aware of the capability of these tools. If you are one of the persons in that group, this article will open your eyes to some of the possibilities these products can bring to your networking environment. One of the most important things you can gain from these products is more stable and versatile information systems. First, let us investigate how these products work. Virtual machine products such as VMWare Workstation 5 and Microsoft Virtual PC 2004 base their success on a common concept. The concept is as follows. 1. Install an operating system such as Windows XP on a physical machine (the host machine). 2. Install the virtual machine application such as VMWare or Virtual PC. 3. Create virtual machines (the guest operating systems) and install the operating system(s) of choice in each virtual machine. 4. You can run several virtual machines at once depending on the hardware. Why have these programs become so popular? Let me count the ways. First, consider the space and hardware costs mentioned above. Why fill a room with several physical machines for testing purposes when a single machine can support four or five virtual machines running on top of the host machine operating system? All of this computing power can reside in a spare corner of a cubicle. The virtual machines are portable and are far easier to build and work with than a traditional test lab. Second, consider the application developers. I have worked with enough developers in my career to know that they usually “blow up” their workstation about once a week or so. That is just the nature of their work. They write code and in the process, the workstation is often a casualty. Before the virtual machine products, it used to be a pain getting them back up and running. You could get them a new image, but it still had to be loaded and it was difficult for them to get back where they left off before it blew up. This process amounted to lost time and effort on both sides. More Reasons Third, as a Microsoft Certified Trainer, I use the Microsoft Virtual PC 2004 for most of the classes I teach today. About a year and a half ago, Microsoft began using the Virtual PC product in many of its classes. This change makes it easier to setup a classroom. From an instructor viewpoint, it is easier to recover if a student makes a mistake during a lab. It is easier to provide the student with a new virtual machine instead of reloading an image. In addition, in a traditional class format, many of the labs required multiple machines with one student per machine. This setup often meant students had to work in groups. One student would do the steps in one part of the lab while others watched or waited. With the virtual machines, each student can perform all the steps of the lab independently of others. Another advantage in the training arena is for situations where the setup requires a triple boot using Windows 98, Windows 2000 and Windows XP. Many of the A+ and Network+ classes require this configuration. A triple boot is difficult to set up and keep stable during the duration of the class. Using virtual machines, the students can run all three operating systems seamlessly on a single workstation. Fourth, many companies are using the virtual machines for program compatibility issues. For example, a mission-critical application may only run on Windows 98. Often, this situation limits or stalls an upgrade to Windows XP. In fact, this was one of the key reasons Microsoft acquired the Connectix Virtual PC product back in 2003. (Microsoft revamped the product and reintroduced it as Virtual PC 2004). They knew many companies were not upgrading to Windows XP due to compatibility issues with legacy programs. One company I consult for actually had two workstations at each person’s desk with switchboxes so they could continue to use the old application on Windows98 and still take advantage of other programs that required XP. With a virtual machine product, they were able to remove the Windows 98 machine and the hassle of the switchbox. This change also made the users happy to get more space under their desks. Fifth, assume you are a network administrator supporting one of these applications that runs fine on Windows 2000, but you are not sure how it behaves with Windows XP. You contact the vendor to find out about compatibility. The vendor’s response goes something like this. “Well, we haven’t run it on XP, but it should work. Oh, and by the way, when you test it, could you let us know how it goes and if you find any problems?” The virtual machine allows you to test interaction between server and workstation client so you find problems before they happen. Hmm. Maybe the vendor could benefit from this technology as well! Conclusion Finally, companies are deploying virtual machines for server consolidation. For example, many companies have four or five servers, each performing a specialized task. One server may do backups, another one monitoring and yet another one is file and print. By using one of the virtual server products such as Microsoft Virtual Server 2005 or the VMWare GSX and ESX Server, many of these roles can consolidate as virtual servers on a single piece of hardware. This use is beyond the scope of this article. Our concentration here will be on comparing the virtual pc product offerings, specifically Microsoft Virtual PC 2004 and the recently released VMWare Workstation 5. Let’s get to it. Here are features about the two products. On the surface, it looks as if VMWare Workstation 5 is the clear winner. However, stay tuned for the next segment in this two-part article: VMWare 2005 vs. Virtual PC 2004 – A Fight to the Finish! In the next article, we will explore how well each of these products goes head-to-head in delivering performance, features and functionality for their assigned tasks. In addition, we will discuss some optimization techniques to help you get the best performance out of each product.