Run a Linux server farm for nix

David M Williams
Monday, 06 August 2007 11:54

Business IT - Open Source

Firstly, a wealth of different environments can be tried. If you want to try out any flavour of Linux you can construct limitless virtual machines without ever having to blow away your main system.

Secondly, you can construct complex server farms on a single piece of hardware. Each virtualised server has its own identity and its own IP address. Machines can pull mail from each other. They can browse web pages on each other. You can host client/server and n-tiered apps. You can experiment with the design of complex networks giving confidence to a proposed solution. Best of all, if anything becomes corrupted you just need to restore a backup of the hard drive file.

Thirdly, should you ever need Microsoft Windows for some purpose you can fire up a Windows virtual machine with greater reliability than that offered by Windows emulators.

Fourthly, all Linux distros are available for download as CD or DVD .iso image files. There’s no need to actually burn these to optical disc. Virtual machines can map the emulated optical drive to an ISO image whether or not the host operating system has support for that filetype.

In fact, you could easily run a whole bank of virtual machines from a portable hard drive – with distro ISO images, virtual hard drives, and virtual machine config files all located onboard. Take these around with you and you don’t just have data, you have actual servers and systems at your disposal.

The three main contenders are VMWare, XenSource and Microsoft Virtual PC, all of which are free or have free versions. Let’s see how they stack up.

Microsoft Virtual PC

Microsoft’s offering is Virtual PC. The latest desktop edition is 2007, which is the only version that works on Windows Vista. You can also download a server edition, Virtual Server 2005 R2. This is the best release and is also free; it lets your virtual machines start up at system boot making them always available and lets you control them remotely via a web interface. Even so both are dead simple to use. Each virtual computer you make runs in its own on-screen window and has its own hard disk file (.VHDs) and configuration settings.

However, where Virtual PC really sucks for Linux use is its abysmal support for X-Windows. I’ve been trying to install Fedora and CentOS and other distros only to find I can’t do anything as soon as the installation tries to fire up X-Windows. With Fedora, I thought the Virtual PC had just locked up. With CentOS, I could vaguely see the outline of what was meant to be displayed.

Depending on your needs, this may not be an issue; you can still run the Linux setup in text mode and you can still set up a Linux system for text terminal usage. Just be sure as soon as your distro of choice fires up that you pay attention to the very first screens. There will be a choice that permits you to install without a GUI, most usually by adding the clause ‘text’ to the end of the boot command. You might also then like to customise the packages that will be installed to make sure X-Windows is excluded. If you are running a Linux distro primarily for server use, then the lack of X-Windows may not prove a problem.
You don’t always have to make your own virtual machines: Microsoft themselves make available a range of VHD files to allow evaluation of their products but these are only Windows systems. Scouring the Internet you may find Linux-based VHDs made by others.

Nevertheless, at the end of the day, Virtual PC is a Microsoft Windows product; it will let you install the OS of your choice but the host environment has to be Windows.