Tuesday, May 27, 2008


VMware (http://www.vmware.com/) is a virtual machine environment that is fast becoming the de facto standard for operating system emulation. VMware allows Windows (and other operating systems) to coexist on the same physical Linux machine without partitioning, through hardware emulation. Hardware emulation is where each operating system has its own virtual area on a system that consists of a processor, memory, disks, and I/O devices. All devices are accessed through the underlying host operating system, and the file system may be a virtual drive that is contained in a file. It may directly access one or more standard File Allocation Table (FAT) 16 or FAT 32 partitions. All access to Linux file systems is done through Samba open-source file and print server software, which supports Windows clients. (A “lite” version of Samba is included.)

VMware can support multiple operating systems on the same machine, depending on the features of the machine: the more memory and disk space and the faster the processor you have, the better chance you have of running multiple operating system sessions. However, only one operating system can be designated as the host operating system. All of the others run as guests on the virtual machine.

Each operating system has its own group of configuration files that must be loaded initially with the operating system. While VMware supports a wide range of devices and options, you need to plan your requirements carefully to ensure that the configuration you end up with is a useful one. Once the operating system is loaded, you can then load VMware Tools to help manage the virtual machine environment.

One of the problems that VMware solves is the need to perform dual booting. Dual booting is an environment where each operating system on the machine has its own partition and set of instructions as to how the operating system should be loaded. Linux users should be familiar with the LILO boot loader, and Windows users with the NTLDR boot loader. In order to move between the two environments, the machine must first be shut down from the first environment, and then rebooted to the new environment. While this is acceptable for occasional movement from one operating system to the other, it becomes bothersome to do this frequently VMware allows faster switching from one environment and-if your machine has enough physical resources-can actually leave the operating system that you designate as the host operating system running while you move to the other environment.

VMware is available as a commercial product but also comes with a few Linux distributions that include the VMware product as part of the install. Therefore, you have the choice of installing VMware on the distribution of your choice or using their prepackaged distribution.

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