Read the article... my views on the author's VMware commets.

Story: Review: Virtualization and Linux--A Primer (Part 2)Total Replies: 2
Author Content
erikb5

Dec 15, 2006
6:58 AM EDT
First my disclaimer. I'm an Consultant that works extensively with VMware products, but I'm also an RHCE certified advanced-user that looks forward to using Xen on RHEL5 (currently beta-testing). My ISP hosting my own website is using the Virtuozzo product. So I do have a grasp of the different technologies.

Carla Schroder comments on VMware : "VMWare uses a different approach to virtualization than Xen. VMWare is an emulator; it creates a virtualized hardware environment for the guest operating systems. Emulation is resource-intensive, but VMWare claims equal or superior performance to Xen."

VMware is not an emulator, it's more an encapsulator. It creates a virtual machine based on a 440BX type motherboard with a set of specific devices. But all the programs and the operating system running in this virtual machine run directly in the host processor. The great benefit of this encapsulation of the vm, is the ability to move a virtual machine from a HP server to a Dell laptop to an IBM workstation without impact.

Programs that are true emulators are named PearPC or Charon (running VAX/VMS code on a PC).

I trully enjoy VMware ESX, because each box I install at a client, is one more GNU/Linux system installed. The Service Console (ie mgmt console) is running a copy/flavor of Red Hat Enterprise Linux 3 on ESX 3 or Red Hat 7.3 on ESX 2.5. I've found that system administrators that have to manage these ESX boxes, find it more and more interesting to study, learn and install GNU/Linux systems rather than their older Microsoft admin consoles.

VMware's enterprise solution is VMware ESX. It's not a free product, but it's powerful, flexible and performant. ESX runs an optimized micro-kernel (hypervisor or the vmkernel) on a specific set of hardware (check out the HCL). It also runs a small Service Console used for management and installation of the product, this is based on Red Hat Enterprise Linux 3.

Hope these few comments and corrections about virtualisation will help you. Erik
jdixon

Dec 15, 2006
8:30 AM EDT
> VMware is not an emulator, it's more an encapsulator.

Well, given how you describe it, that's technically correct, but it's really a matter of how you define your terms. I believe Carla's usage is considered correct by the normal definition of the term.

I agree that VMware is sweet, BTW. I've used Player at both home and work. I still need to take a look at Server when I have some free time. Unfortunately, they've never seen fit to release a version for Slackware, and while it's possible to make it work, it's not normally worth the effort.
swbrown

Dec 15, 2006
1:30 PM EDT
"VMware is not an emulator, it's more an encapsulator. It creates a virtual machine based on a 440BX type motherboard with a set of specific devices."

It emulates the hardware, so it's an emulator. You pay the emulation cost for using it, and lose hardware features where emulation has taken place at a lower standard (e.g., professional sound cards all wind up looking like an old AudioPCI soundblaster). Significantly different approach than Xen.

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