Linux in Government: VMware Workstation 5
VMware Workstation 5 allows multiple operating systems and applications to run at the same time on a single physical computer. If you have a lot of RAM, a large hard drive and a serious CPU, VMware performs okay. In this way, it is more of a developer's product than an end-user one.
The guest operating systems live in isolated virtualized machines. VMware maps a hosts computer's hardware resources to the virtual machine's resources, so each virtual machine has its own CPU, memory, disks and I/O devices, so to speak. Each virtual machine appears to the guest operating systems as a standard x86 computer.
Once VMware Workstation installs a guest operating system on the host, you can install and run unmodified versions of Windows, Linux, Novell NetWare and Sun Solaris x86, as well as applications written for those platforms, on one machine. VMware says users can see the benefit of using multiple PCs without the expense, physical setup and maintenance of various hardware platforms. By the time you build a machine with enough resources for the guests to operate at acceptable level, you could have saved money buying separate PCs. But VMware has other advantages at which we should look.
Figure 2 provides a look at VMware Workstation running on NLD 9 with Windows XP Home Edition installed. This should give you an idea of what you can expect to see if you use this product. Notice on the top of the tool bar that an icon lets you select a full-screen mode. By selecting this option, the guest occupies all of your monitor's pixels. It's still not going to give you the benefit of a great visual experience, however.
The virtual hardware of VMware 5 runs better than previous versions. With a single Pentium IV or an equivalent AMD processor and 512MB of RAM, one should be able to run two virtual machines simultaneously. The previous versions would grind to a halt in such a scenario.
I wouldn't recommend running your system that way, however. If you have a need to run more than one virtual machine, you should run dual high-end processors and 3GB of memory. Otherwise, you cannot use your host machine and the two virtual machines with any efficiency.
Snapshots of an OS
Version 5 provides for multiple snapshots so a user can take a snapshot at any point and revert to its original or another state when a guest is powered down. Users can configure a virtual machine to take a snapshot when a guest is powered off and preserve an audit trail. If you need to examining a virus, for example, you can take a snapshot before you introducing the malware. If you the virus does damage, a user can restore the virtual machine to the state preserved in that snapshot. The same goes for testing new code or a patch.
Previous versions of VMware allowed for the taking of snapshots. However, once you created a second one, it would overwrite the original snapshot. So, for testing purposes, version 5 provides a significant upgrade.
Workstation teams allow users to set up a virtual network or lab on a host computer. You can power up multiple virtual machines as mentioned above. You then can configure networking the way you would on any local area network, however, this network would run on a single computer.
Users can work together in what VMware calls a LAN segment. They are invisible to the host computer's network, which creates the possibility of doing development in a virtual safe house.
The new VMware Workstation provides interesting deployment capabilities with what the company calls clones. In VMware workstation terms, two types of clones exist. One it called a full clone, which we might consider to be similar to a ghosted image used to provision another computer. The second type of clone is called a linked clone. It remains dependent on the original image.
VMware's full clone functions as an independent copy of a virtual machine. Once a user makes the clone, it runs separate from the parent. It then can go off and become a unique instance that you can use to make changes or deploy for whatever purpose you see fit.
VMware's linked clone shares virtual disks with the original or parent, conserving disk space. This permits multiple virtual machines to use the same software installation. Also, linked clones take less time to create than a full clone does.
Labs might want to create linked clones to provision to developers, quality assurance engineers, testers or maintenance programmers--literally for different tasks. By storing a linked virtual machine on your local network, other users quickly can make a linked clone. A support team can reproduce a bug in a virtual machine, and an engineer quickly can make a linked clone of that virtual machine to work on the bug.
The files on the parent of a linked clone continue to exist at the time one creates a snapshot and continue to remain available to the linked clone. Changes to the parent don't affect the linked clone, and changes to the disk of the linked clone do not affect the parent.