Introduction

VMware is a company that provides a software that emulates a virtual computer. Let's assume for simplicity that we have an existing machine with MS Windows. This is called the host machine. One needs to install the vmware software (see Installing the VMware Player) on this host machine. Once the software is installed, it can be started like any other application. Once this virtual machine software is running, it will simulate a PC environment so that one can have a second (virtual) machine running in that window. The 'virtual' hard drive of that virtual machine is realised through a (few) big files gathered in a particular directory on the hard drive of the (Windows, say,) host machine. It is of course required to provide an operating system for the virtual machine, which could be, for example, Linux.

One would then have the normal MS Windows Operating system running on the host machine, and a Linux operating system in the VMware window. (In fact, the window can be blown up to appear as a full-screen, by pressing CTRL+ALT+Return, or clicking of the maximise icon of the window.)

The performance penalty of running any software in the virtual machine (rather than on a real machine of similar specification) is usually less than 10%. In other words, a simulation that takes 10 minutes in the virtual machine, is not going to be faster than 9 minutes if run natively. However, 3d graphics may not be hardware accelerated in the virtual machine; and the virtual machine will only see a part of the physical RAM of the host machine (this can be adjusted in the vmware settings when the virtual machine is shut down).

The nice thing about having this virtual machine is that one can continue to use one's email, word processing, web browsing and all other applications in one's usual operating system (Windows in our example), and simultaneously have a simulation environment for micromagnetic simulations (which provides all the necessary pre and postprocessing tools, based on the Linux operating system here).

In terms of performance, the host machine should have at least 2 GB of RAM (the more the better). The virtual machine is set to use 1.5 GB RAM and 1 processor core. It currently needs about 7GB of disk space on the host machine.

Installing the VMware Player

VMware provides a multitude of different products that allow different degrees of virtualisation. Some of them are free and some have to be paid for. We try to point to exactly the right product here, and to keep things simple although VMWare is frequently changing the names of their products.

If your host runs MS Windows or Linux, then you can download the free VMware Player:

• click on the Download button
• click on Download now button
• At this stage, VMware asks you to provide some information to profile their customer base. Complete the form and click Submit.
• click on the Download now button
• Agree to license agreement by pressing Accept
• Select the right version to download:
  • If your host runs MS Windows, then download the latest version of the VMware Player for Windows
  • If your host runs Linux, then chose
    • .rpm for red-hat based systems, or
    • .tar for all other Linux systems
• After having downloaded the file, install it as you install any other application for your operating system (i.e. for Windows, double click on the executable) and follow the instructions.

If your computer is an IntelMac, there is unfortunately no version of the free VMware Player for your machine. However, if you happen to own VMware's Fusion product (or are happy to pay for it), then install VMware fusion and use this as (a more powerful) VMware player.

If you computer is a PowerPC Mac, then you cannot use the Virtual Machine method.

At this stage, we have installed the VMware Player. Next, we need to obtain the 'virtual machine' that we want to execute.

Downloading and starting the Nmag virtual machine

• Download the zipped Nmag virtual appliance from this directory.
• unzip the downloaded files: extract they content into a subdirectory with name nmag-0.2.
• start the VMware Player software
• Within the VMware Player window, select Open or Browse to
  • locate the directory into which you have unzipped the virtual machine.
  • change into that directory and
  • select the file ending in .vmx to open (for example nmag0-2-Ubuntu64_1.vmx)
  • and click open.

When you do this the first time, the VMware Player may warn that the machine is already in use. If so, select Take ownership.

It may ask you whether this virtual machine has been moved or copied. The right answer is copied.

Once you have done this, the virtual machine will boot.

When the kernel boot menu appears (the first line starts "GNU GRUB"), do nothing, or press return.

Wait until the graphical login turns up.

Using the Nmag virtual machine

The Nmag virtual machine is an Ubuntu64Bit 11.10 installation which should provide all the software required to run micromagnetic simulations with Nmag.

After booting, a login screen appears. There is only one user registered. The username is nmag and the password is nmag. (The root account has the same password; should you ever need it.)

At this point, you have a complete environment to start simulations, and the guided tour in the manual is a good starting point to explore nmag:

• Click CTRL+ALT+T to get a terminal (a shell window).
• You find a link on the Desktop (nmag-manual-html.sh) which will display a local copy of the manual on your harddrive (select Run after double clicking).

If you want to see the examples that are discussed in the manual directly, you can go to /home/nmag/Desktop/nmag-examples-drafts. Each subdirectory in there corresponds to one example. Note that there are sometimes additional files in the directory that are used for automatic creation of plots in the manual, and for automatic testing (you may want to ignore those). Some file may be out of date, but overall this is a useful resource to run some existing scripts quickly. Often, there is a makefile or Makefile in a example directory, which summarises the commands that can be run to create a mesh, convert it, important it, run a simulation etc.

First steps

1. Login as nmag, password nmag.

2. Double click on nmag-manual-html.sh`, then ``run to display the Nmag manual.

3. Navigate to example 1 in the guided tour (Example: Demag field in uniformly magnetised sphere).

4. Open a terminal (either through clicking on the terminal icon at the side bar, or pressing CTRL+ALT+T)

5. change into the directory with the manual examples by typing:

   cd Desktop/nmag-examples/drafts
   

6. change into the directory for the first example:

   cd example1
   

7. run the simulation that is described in the manual by typing:

   nsim sphere1.py
   

   (When you run this the second time, you will need to use nsim sphere1.py --clean to allow overwriting of existing data files.

Using VMware player

The help function of the VMware Player provides a useful summary of how to use it.

Note that you can switch to full-screen mode when pressing CTRL+ALT+RETURN, and that you return from full-screen mode by either pressing CTRL+ALT, or moving the mouse to the top of the screen (to get the VMPlayer menu).

Frequently Asked Questions