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Last updated: 14 Nov 2012
Creating User-Defined VMs
Background
Most lab workstations are Linux hosts that are able
to run at least one virtual machine or VM.
Windows runs as a guest
operating system and provides a standard learning and coursework environment.
It is defined and configured by Institute lab staff.
There may be times when you want to create your own VM -- a
user-defined VM.
There are two ways to do this.
- VM on Windows host
All lab workstations running Windows natively or as a guest can
also support creating VMs inside of Windows, using Oracle's VirtualBox
virtual machine manager. These VMs run within your Windows
login account and should not continue to run
after you log off.
- VM on Linux host
In non-general development labs,
you can also create VMs that will stay up until
you stop them, for research and special projects
work. These VMs run under a special Linux account, and can either
replace or add to other VMs running concurrently. That is,
if you don't need the standard Windows VM, you can
stop the VM
and run just your VMs. Typically, you stop the provided Windows
VM when a lab workstation is not shared but dedicated to your work.
Stop the Windows VM
The predefined Windows VM can be stopped by:
- Logging into Windows as usual
- Opening a CMD shell
- Entering:
g:\stop_vm
- Logging off
- When the "Press Ctrl-Alt-Del" screen is shown:
- Enter Ctrl-Alt-Del
- Press the Enter key or click OK
- Click on the red button in the lower right=hand corner and shutdown
the VM.
Once the Windows VM is shut down, you should be able to login to
one of the provided accounts.
Creating a VM
VirtualBox provides two ways of creating and managing a VM: via the
VirtualBox GUI, or via the VBoxManage
command line. You'll likely find the GUI much more pleasant to
use than the command line, but the command line can do much more
than the GUI allows -- something to keep in mind as the complexity
of your VM grows.
VirtualBox is started from either the command line (e.g., in Linux:
VirtualBox &) or by searching for the
VirtualBox application, then clicking on the application's
icon. Either method brings up the same VirtualBox GUI.
- Click on the New button.
- Name and operating system
Provide a name, and select the type of OS and the OS version
corresponding to that OS. In addition to the unmarked 32-bit versions,
you can also select 64-bit versions.
The OS selection helps VirtualBox optimize its operation for that OS.
- Memory size
Specify how much virtual RAM you want to provide to this VM.
While the recommended amount is usually adequate for light student
use, you might want to increase the amount; stay within the "green
area" to avoid conflicting with the RAM needed by the host operating
system to run. Also keep in mind how many VMs you will be running
at the same time. For best performance, try to keep the total RAM
that all VMs use to within that same green area.
- Hard Drive
If you will be using a "live" CD or DVD, you don't need to create a
virtual hard drive (unless you will want to install that live CD to
disk later).
Usually, you will want to create a virtual hard drive now,
though you can always create one later and attach it to your VM.
- Hard drive file type
Choosing the VDI hard drive file type is a good,
safe bet.
- Storage on physical hard drive
Using the default dynamically allocated storage
is usually the best choice. A smaller size (vs. a fixed size) makes
copying a VM faster.
- File location and size
Normally, the name of the virtual disk is the same as the VM. That
works for one disk per VM, but if you want more than one, you'll
have to add them later... and the names will need to be different.
The size of the disk depends on what you want to do with it.
Windows 7 or 2008 require at least 20GB with updates and a couple
of apps installed.
After that, you should see your defined VM, which you can further
define and tweak using the Settings button
(make sure your VM is selected first!).
The next step after creating a VM is usually attaching a virtual CD/DVD
to it, in the form of a file that ends with .iso
-- an ISO file. While
you can use a real CD/DVD on a dedicated computer, virtual ones
are used on remote computers to avoid excessive network traffic,
so it is often a good idea to use an ISO file instead.
Also, it is faster to use an ISO file than a real CD/DVD.
For example, let's say you created a 32-bit Fedora Linux VM, and want to use
the Fedora 17 Live CD ISO file to boot up.
The file path is /home/labadmin/Fedora-17-i686-Live-Desktop.iso.
- Click on Storage
- In the Storage Tree:
There is a storage controller called
Controller: IDE.
It is a virtual IDE controller —
a disk and CD/DVD controller that was popular before SATA controllers took
over the market.
- Click on the Empty CD/DVD icon.
The Attributes will change to show the
CD/DVD Drive.
- Click on the CD/DVD icon with a small down arrow on it
to the right of the CD/DVD Drive.
- Select Choose a virtual CD/DVD disk file....
- Navigate to and select the
Fedora-17-i686-Live-Desktop.iso file.
- Click OK to virtually insert the virtual CD/DVD
into the virtual drive.
Now you can start your VM, which should boot up to the CD/DVD (if it's
bootable) or the hard disk (if it has an OS installed).
Managing a VM or Guest OS
- Install VirtualBox Guest Additions
You'll find working with the VM much more pleasant if you install
the guest additions, but how to do so is beyond the scope of this
document.
- Do not install or use software that you don't have the license to use
You must not install software that the UW does not have a license to use.
Some software has use restrictions, such as it cannot be used for
funded research or for developing commercial products.
- Update the OS
Once you install an OS to a virtual hard disk, you
are a "system owner" and have the
responsibility to maintain the security of that OS, per
UW Security Policy.
One of the simplest and most effective things to do is to
update the OS to its latest patches. This means running
Windows or Microsoft update on a Windows VM, and
using the corresponding software updater on a Linux VM.
Update the operating system and the applications installed within it.
Updates should be run periodically if they can't be
configured to run automatically.
- Install antivirus tools
The UW provides antivirus tools for
Windows,
Mac, and Unix/Linux. Installing them can help prevent malware
from infecting your VM.
- NAT vs. Bridged networking
The default networking type is NAT, or Network
Address Translation. NAT uses the existing network interface controller
(or NIC) on the host to provide access to the
network from within your VM. If all you are doing inside your VM
is browsing the web, using network client software (such
as ssh or SQL Server Management Studio),
or pinging other computers, NAT is a good solution and doesn't require
any configuration. In addition, it doesn't use up any IPv4 addresses.
However, using NAT means that your VM doesn't have a real IP address in
the sense that it can be detected by another computer. This is a problem
if your VM will be used as a server, and needs to expose its IP address
and ports to use to the network. While you can still do that with
NAT, you would need to use non-standard ports and set it up specially
in VirtualBox (Settings/Network/Adapter 1/Advanced/Port Forwarding).
If your VM's guest OS must use standard ports (e.g., port 80 for a web
server or port 22 for the ssh daemon), you should change your VM to
use bridged networking
(Settings/Network/Adapter 1/Attached to/Bridged adapter).
A bridged VM will appear as if it is directly
attached to the network -- if it uses dynamic IP addresses, it will
get an IPv4 address from the network's DHCP server. If you have
a static IP address assigned to you, you could use that inside your
VM.
- Stopping a User-defined VM
It is usually better to gracefully shutdown a VM (or any computer)
than to essentially pull the plug (poweroff or reset). Often,
choosing the VirtualBox menu item Machine/ACPI Shutdown
will perform a graceful shutdown. Also, you can use the OS's shutdown
features to do the same.
Powering off or resetting
a VM should be used as a last resort, as it may corrupt
the virtual disk(s).
- Backup your data
Nothing will be backed up for you, so you are responsible for making
your own backups. Since the host's physical disk could fail, you could
lose all of your virtual disks, so don't rely on the host's disk for
your backups. Instead, use an external drive, and make another copy
to a second external drive once per week.
Change Log
14 Nov 2012 |
Original document |
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