The other thread is
I started getting curious about virtual machines when the IT guys at my campus started talking to me about it. I think we may eventually use virtual machines as a way of cutting back on hardware costs and possibly even allowing a real-time back-up solution of our running installation.
So one question seems to be what virtual machine system to use. I have successfully installed the Live DVD of WeBWorK on a virtual machine created using VirtualBox (supported by Sun Microsystems). I believe that VirtualBox is available for multiple platforms (either Windows, Mac or Linux) and more importantly it seems to be free for educational use. I don't know how it fares performance-wise against the others but I found it fairly easy to set up.
For what it is worth (and not saying I understand the details really), the IT guys that I work with seem to want to use VMWare. They seem to think that it would offer the best possibility for seamlessly switching a virtual machine based on one physical server over to another. I gathered that they meant seamlessly in the sense that users would not really even be able to tell that the virtual machine (or the guest system) had changed hosts while they were using it.
A couple of other thoughts on my mind about virtual machines that may be pertinent.
1. Be sure your system has plenty of RAM. You need as much RAM as the host system requires plus as much RAM as you want to designate to the guest system. For this reason, I would think that virtual machines would be best accomplished using 64-bit processors with 4+ GB of RAM. The more the better.
2. Hard drive space is important. When you create a virtual machine, you are creating a massive file that can easily be larger than 4GB. Hard drives today can easily handle this but the file need to get larger over time. I would think that good consistent defragmentation of the harddrive might be important for this reason.
Any other comments or experiences that people have had to add to this?
thanx for forking the discussion. Since I guess, You like Unix like systems, You could use VMWare Fusion for MAC OSX. That way, You don't have to worry about defragmetation, but anyways, my experience with VM Ware is completely positive. I have several very important servers inside VM, and I did not defragment disk. Never. I keep redundant Domain Controler, SQL 2005 and MS ILM Server inside VM Ware's Server 2.0 . No problems, for now.
Question for You regarding VirtualBox. Is it available for SPARC III & Solaris 10? How hard is the instalation process ?
I haven't tried VMWare or Virtual PC yet (from what I can tell, Virtual PC does not "officially" support linux as a guest OS). VirtualBox is a free download and so it was convenient to try. According to their website it is available for Windows, OSX, Linux, and Solaris. They have two versions that are available: an open source version (OSE) and a PUEL version that does a little more. Both are free for educational use. The source code is available for the OSE version, so I imagine you could build it on a SPARC system. I haven't had any experience with this however, so I can't say for sure.
In terms of installing, I can only speak about my experience on Ubuntu. It was pretty easy. They had already created a .deb file so apt-get made it easy to install with any of its dependencies. Ubuntu 8.10 (the latest version as of now) also comes with the package for the OSE version among its package list making it pretty easy to install using the package manager on that system. I followed the directions on the following page at the website:
virtual box download and install
A variety of distributions can found at the following pages: download info or distribution directory listing
After it was installed, there was an option under my application menu to use the "Sun xVM Manager" (or something like that). To install a guest system, it is easiest if you have an .iso of that system's install disk available.
About disk fragmentation, I brought this up because I recently became aware that Vista does defragmentation automatically. However, apparently its default setting is to only defragment files that are smaller than 64MB (can anyone verify this?). I would think that this could eventually be a severe hindrance to a Windows server that was running virtual machines (which require large file sizes to emulate a hard drive).
I can say that from the administrative side using a virtual machine is great. If I need to do an update I just take a snapshot first and update without (much) worry, if the update doesn't work out I can always go back to the snapshot. Other than having to negotiate with IT over our virtual memory allotment the system has worked very well.
I should point out that we run a small system: we have less than 200 students on webwork a semester. If you have other questions I could get one of our IT guys to answer them.