Revisiting VMware 1.0

This goes back to a time when i started with VMware.

Thanks to german c't magazine for keeping it online.

c't 14/99, page 54 - VMware 1.0

Peter Siering

Integrator

VMware 1.0: Windows with Linux

No missing out on popular operating systems and the respective applications for people who like working with Linux any more. VMware under Linux simulates a PC inside a PC and runs DOS, Windows & co in it.

Compared to its previous version (see c't 7/99), VMware has essentially been fine-tuned and, for example, problems with German keyboard settings have been eliminated. What's a real bonus is that MVware have re-thought their pricing and are now offering a competitive version for private use.

VMware uses the host operating system's (currently Linux) resources only for providing an independent PC. While traditional emulators make a big effort to mirror one operating system's functions onto another, VMware doesn't even try. Sufficient performance provided Windows & co will run flawlessly in the X window.

VMware recommends a system with 64 MBytes of RAM and a Pentium II with 266 MHz. For everyday use, a normal Pentium should do the trick. Sufficient main memory is essential. There should be physically enough for both host and guest system(s) to breathe freely and for none of the systems to be forced to relocate data. With current Linux systems (kernel 2.2.x), VMware profits from an additional CPU. However, only the host system will benefit. Only one CPU is available to the guest systems.

Start Me Up

The software is a modest 2 MB in size. Utilities for Windows 9x and NT as well as for Linux as the host add another megabyte each. VMware distributes its software exclusively via its web site (www.vmware.com). Anyone registering online will receive a free 30 day trial licence. You can only buy VMware online, too, a credit card is required.

Until mid-July, a commercial licence will cost US$199.- (US$299.- after that) per user. A licence for private use only is currently available at US$75.- (US$99.- later). VMware operates its own news server (news.vmware.com) to support all their customers.

The software, which comes as a tar.gz archive, is installed (and updated, if required) with a Perl script. This worked fine with a popular distribution, I used SuSE 6.1. During startup, VMware asks whether to start a simulated PC called a virtual machine (VM) or set up a new configuration. A wizard helps by offering several standard configurations.

When starting a virtual machine (VM), the usual PC messages appear on screen. BIOS is supplied by Phoenix. If there is a boot disk in the drive, the system will start the usual installation procedure, for example of NT, but will do so in an X window. Guest systems will find a classic PC with two IDE ports, serial an parallel interfaces, VGA board, sound blaster and AMD network board in a VM.

VM devices are independent of the actual hardware setup. For example, there might be a Microsoft sound system installed under Linux, but Windows in a VM will still see a sound blaster board, etc. Only a VM's CPU will always correspond to the actual host system setup.

Physical ports and resources may be allocated at random in a VM, VMware could, for example, provide the first serial port in Linux (/dev/cua0) to a VM at COM3. Each of the four (virtual) IDE ports can accomodate either a CD ROM drive or a 'virtual' drive. A virtual drive may be either an image file which is adjustable in size to meet the respective requirements or a disk or partition (for example /dev/sda or /dev/sda5) actually installed in the system which may be used transparently by the host system.

Virtual disks which are mirrored onto files by VMware can currently only be up to 2 GBytes in size (a restriction caused by Linux's own ext2 file system). For setting up virtual disks - be it image files or actual partitions - VMware offers three options: Changes may be executed directly (persistent), they may be integrated only at the end of a session and upon request (undoable) or they may automatically be discarded (non-persistent). The latter option serves for booting an existing Windows installation besides Linux - any changes, for example caused by new devices which are bound to be recognized in this case, will be discarded by VMware.

On the network side, VMware again offers two options. Operation mode 'bridged' uses the Linux system's network board as a bridge. Data will be forwarded by VMware (provided the respective board offers promiscuous mode). This way, a VM Windows installation will communicate with a LAN independently from the host system and get, for example, the IP address, and it will also be present as an individual system, for example for enabling file and print services.

In its second operation mode (host only), VMware can build a virtual LAN within the host system. Every VM is equipped with its own interface to communicate with other guest and the host system. Therefore, neither leads nor additional computer are required if you need a Windows client and a Linux server for developing software. Given the right routing, the virtual network can also be integrated in existing LANs.

Perfectly Happy

VMware provides almost anything you could wish for. The only thing missing is direct data transfer between a VM and Linux. For this purpose, VMware only offers the network (which may be purely virtual). Therefore, suitable file server software to ensure VM access to the Linux file system is essential. Mounting files as file systems via loop device, although common practice in Linux, is something VMware cannot do because it uses a proprietary format for its image files. However, VMware has signaled improvements here.

VMware 1.0 currently supports DOS, Windows 3.x, 9.x and NT 4.0 as well as Linux and FreeBSD as guest operating systems. A preliminary version (build 179) only available to registered customers supports the current Windows 2000 beta as well as Solaris for Intel, Netware (client and server) and DR-DOS. BeOS and OS/2 are still unsupported. However, VMware does not recommend using this preliminary version but regards it as a demo version for version 1.1. Registered customers will get a free update for this new (minor) version.

For using DOS, Windows 3.1 and FreeBSD VMware doesn't provide any additional software. This means that anyone wanting to work with these systems must make do with standard VGA resolution. It is different for Windows 9x, NT 4.0 and Linux: Here, special VMware utilities make sure you can activate any resolution up to the host system's own in a VM. For Windows, there is an accelerating graphics driver, for Linux a special X server. It is possible to switch a VM into full screen mode but accelerated access requires a special X extension for the host system which VMware again offers for downloading.

I tortured both Windows 95 and Windows NT 4.0 in VMware with the benchmark BAPCo SYSmark 98. Not only does this give an impression of the Windows performance we can expect in a VM, it also shows how compatible and stable Windows actually runs under VMware control.

According to BAPCo, performance actually is what it seems to be: With a 266 MHz Pentium II system, Windows 95 is about as fast as on a 133 MHz Pentium (Rating 42), NT 4.0 is as fast as on a 200 MHz Pentium (Rating 70) (measured with 64 MBytes RAM each for the VM and 128 MBytes of physical memory). Compared with BAPCo's result (rating 113), these VMware results are not sensational but they are well suitable for everyday use.

And there is added value in its stability: Despite several BAPCo runs of NT 4.0 under VMware, there wasn't a single crash. With Windows 95, there were the usual hiccups you also get without VMware.

I didn't investigate Linux's performance within a VMware VM any further. According to our affiliate iX magazine, it mainly lacks disk performance. This also explains the rather disenchanting BAPCo results. In a short functional test, MSDOS 6.22 worked well with the DOS client Microsoft provides with NT servers. Installing FreeBSD didn't cause any problems, either.

Working with VMware's X window requires some getting used to. Installing VMware utilities in Linux at least releases the mouse (without utilities you must free it via a combination of keys). Yet using it with SuSE 6.1's KDE caused the strangest effects. Instead of the window which is shown as selected, VMware keeps the focus. In addition, the screensaver could only be closed after having removed VMware's focus (with a keyboard shortcut).

Things get naughty when VMware encounters defective CD ROMs: The PC seems to pack it in. However, all that's needed is to change to a text console and shorten the wait by killing the VMware process. The usual Windows annoyances don't impress VMware much. For example, it simply displays the NT Bluescreen without interfering with the host system.

Fit For Everyday Use

This makes VMware the only practicable approach for using Windows applications with Linux. Developments like Wine or Wabi can't keep up with it. For occasionally using DOS with Linux, I will stick to dosemu, however. It is more convenient especially for using older developing environments, for example with 43/50 line display.

Anyone frequently testing various operating systems will find VMware an ideal playground. The image file installations can be saved in any form and hardware-independently. Therefore, they can be transported from computer to computer.

Having several operating systems running simultaneously as if they were on separate computers is unique. If you want to simulate less complex network scenarios for testing purposes, this is the ideal solution. I am dying to see VMware's version which uses NT as its host operating system. It should give every NT user the option of taking a look at Linux - unfortunately, VMware have delayed the beginning of the test phase until early July 1999. (ps)

Translation by Eva Wolfram

[source: http://www.heise.de/ct/english/99/14/054/ ]