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VMware: my new best friend

You can't be too rich or have too many computers. These days, I'm not feeling too rich, but I still want to have lots of computers. What's a poor geek to do?

This year, the answer for me has been a software packaged called VMware.

I use VMware for Windows V3.1 on top of Windows 2000; there's a version for Linux as well. VMware is a "virtual pc": I can use VMware to install and run other operating systems. (VMware refers to Windows as my host OS; any other OS I install is called a guest OS.) I can boot up a copy of Redhat Linux, FreeBSD, or even another copy of Windows. When I run a guest OS under VMware, VMware fools that guest OS into believing it's running on a physical piece of hardware: VMware's "virtual pc" has an Ethernet card, a hard drive, a CD drive, a keyboard and mouse. I can install multiple guest OSes, and run up to four at the same time; the primary limitation is how much disk space is available under Windows.

Installing an OS under VMware has advantages. VMware supports only a limited number of devices which are widely supported; to the guest OS, VMware appears to be a vanilla pc. VMware allows you to suspend and resume virtual machines. VMware does physical machines one better: you can set VMware up so that when you shut down your virtual machine, you can choose to discard all changes to disk since the guest OS was booted. I have a test install of Windows 98: under VMware, I can boot it up, install an application to test, and when I shut down Windows, I can restore the Windows 98 system back to the same state before I installed the application.

There's no free lunch, of course. VMware is a Windows application; what the guest OS sees as a hard disk is really a (big!) file under Windows. VMware is a memory hog: if you allocate 128Mb to a guest OS, VMware will typically suck up somewhat more than that while it's running. An operating systems running under VMware is always slower than it would be if it was running natively on your PC.

When I first used VMware back in 1999, my main PC was a Pentium 2/266. The Pentium 2 just wasn't fast enough; using a guest OS was painfully slow. This year I fired up the latest version of VMware and found to my delight that VMware ran decently on my home Pentium 3/500Mhz box.

At work I've got a Dell 2.2Ghz Pentium 4 with 512Mb memory and 2 40Gb disks. VMware rocks on the P4. My guess is that software runs about 50% of normal speed under VMware. That sounds bad, but that means is that running Linux under VMware on the P4 is the equivalent of running on 1Ghz P3. In any case, it's the fastest Linux box I've ever had access to.

My home Linux box is a (physical) 133Mhz Pentium. Linux running on any of my other PCs beats that box handily. Here are some example times to compile Emacs 21.34 on several different systems: the P/133, Linux under VMware on my P3/500, and Linux/VMware on the P4/2200. All systems run Debian 3.0 Linux with 64Mb of memory.

• Pentium 133/64Mb memory: 19m 34s
• Debian 3.0 Linux under VMware for Windows, 64MB hosted on P3/500Mhz/256Mb ram: 3m 30s
• Debian 3.0 Linux under VMware for Windows, 64MB hosted on P4/2.2Ghz/512Mb ram: 0m 50s

I.E., it took 19.5 minutes to compile Emacs on my Pentium I, and only 50 seconds to compile Emacs running Linux under VMware on a Pentium 4.

On my Dell at work, I have the following OSes installed under VMware:

• A Debian 3.0 server for a work project (I leave this running all the time)
• Redhat 7.3
• Redhat 8.
• Windows XP
• Two more Debian 3.0 instances. I have a third Debian install I haven't loaded yet, and my intention is to run all three Debian instances at once so I can test out using Debian as a firewall.

All those installs don't run at the same time, but you can have up to four guest OSes booted at once. All told, those 6 OSes are taking up 14 gig of disk under Windows 2000. (I've still got 26gig disk free on that drive.)

In a previous post I mentioned that I tried out Linux From Scratch out a "1 Ghz Pentium box." That "box" was actually running under VMware. Trying out LFS was no big deal. I didn't have to cannibalize an existing box, I didn't have to worry what would happen if I could get the box to boot again. All it cost me was some disk space. I'm in geek heaven.

VMware is more than a neat geek toy. When I first started at Georgia Tech, I started a weblog to document my work. I put that weblog on my home Linux box. After a month or so, I needed to move it to work on short notice, but I didn't have a place to put it. I installed VMware on my Dell desktop box, installed a Debian instance under VMware, used a DNS CNAME alias to point to the Debian install, and was off and running. (VMware guest OSes can have their own IP addresses which make them indistinguishable from any physical machine.) Later I found a home for my weblog on a Tech supported box; I moved the CNAME from my Debian box to the Tech Solaris box, and everything worked.

As a point of interest, my guess is that more people use VMware for Linux - with a Linux host OS. Many of those folks use VMware with a Windows guest OS so that they can have access to Windows applications. My observation is that Windows runs better as a host OS than a guest OS - or put another way, Windows needs all the horsepower it can get, so running it natively is better. Linux is much lighter weight. You can run X Windows with Linux under VMware, but I typically don't bother: I use an terminal emulation application under Windows to talk my VMware Linux guests. Works great, and I can get by with giving Linux 64 or even 48Mb of memory.

Perhaps the biggest disadvantage of VMware is the price. It's $299 for either the Windows or Linux version - the two are separate products. When I bought VMware in '99, there was a lower price for individuals, but that seems to have gone away. You can still get VMware for around $150 if you're a student.  Upgrading my license to V3.1 was around $100 earlier this year. Still, even though I was unemployed at the time, I still decided it was worth the money: VMware allowed me to keep up to speed technically while I was out of work.

For another view, check out Krzysztof Kowalczyk's review of VMware.

Last update: 4/8/2003; 9:01:52 PM.