Virtualbox: Difference between revisions
| Line 18: | Line 18: | ||
== Virtual box guest addition == | == Virtual box guest addition == | ||
=== Debian === | |||
Install guest addition for virtualbox on Debian | Install guest addition for virtualbox on Debian | ||
See the link [http://virtualboxes.org/doc/installing-guest-additions-on-debian/] | See the link [http://virtualboxes.org/doc/installing-guest-additions-on-debian/] | ||
Revision as of 08:05, 1 September 2015
Installation on Ubuntu
Check if hardware (CPU) supports virtualization
egrep -c '(vmx|svm)' /proc/cpuinfo
- If 0 it means that your CPU doesn't support hardware virtualization.
- If 1 (or more) it does - but you still need to make sure that virtualization is enabled in the BIOS.
If your CPU does not supports hardware virtualization, you can only install 32-bit virtual machines (not 64-bit).
Virtualization in the host machine
Note that even the host machine is 64-bit, if the vT is not available/enabled in the BIOS, we cannot install 64-bit OS in the guest machine.
A caution about Ubuntu guest machine
The regular Ubuntu OS uses 'compiz' which takes too much CPU power (50% to 100%) in virtual machine. Better to use others like xubuntu or lubuntu.
Virtual box guest addition
Debian
Install guest addition for virtualbox on Debian See the link [1]
The instruction is helpful on Debian w/o a graphical desktop.
- Login as root; Or type 'su' and the required password to log in as root.
- Update your APT database with apt-get update;
- Install the latest security updates with apt-get upgrade;
- Install required packages with apt-get install build-essential module-assistant;
- Configure your system for building kernel modules by running m-a prepare;
- Click on Install Guest Additions… from the Devices menu, then run mount /media/cdrom.
- Run sh /media/cdrom/VBoxLinuxAdditions.run, and follow the instructions on screen.
We can check the extension pack version or if it was installed by going to the File -> Preferences -> Extensions.
virtual machine software benchmark
Trouble Shooting
Forum
Old builds
When it is impossible to find a solution for some unknown errors when installing a new build of VB, it is worthy to go back to install an old build of VB.
The old build & extension pack of VB can be downloaded from https://www.virtualbox.org/wiki/Download_Old_Builds.
For example, I always got an error 'supR3HardenedWinReSpawn'. The log file shows something like
13d8.c54: supR3HardenedMonitor_LdrLoadDll: error opening 'C:\Windows\system32\wintab32.dll': 0 (NtPath=\??\C:\Windows\system32\wintab32.dll; Input=C:\Windows\system32\wintab32.dll)
The only solution is to install an old version of VB.
the headers of the current running kernel were not found
sudo apt-get install dkms build-essential linux-headers-$(uname -r)
virtualbox failed to create the host-only network
Virtualbox (*.deb) was downloaded from virtualbox website. However, when I want to create a host-only network, I have to execute
sudo /etc/init.d/vboxdrv setup sudo apt-get install dkms build-essential linux-headers-$(uname -r)
This also solves the error "Kernel driver not installed (rc=-1908)".
Ubuntu 14.10 guest machine
Especially, if my host is already Ubuntu, I want to use RightCtrl + F1 and RightCtrl + F7 to switch between the terminal and the graphical desktop. If my host is Windows OS, I can use Ctrl + Alt + F1 and Ctrl + Alt + F7 to switch.
Error 0x000000C4 & Windows 8.1 guest machine
The problem happened on my Xeon CPU Windows & Ubuntu machines, but not my Pentium cpu Ubuntu machine.
The solution is to run the following line (remove the path if it is run under Linux) first before installing Windows 8.1.
“c:\Program Files\Oracle\VirtualBox\VBoxManage.exe” setextradata “<Virtual Machine Name Here>” VBoxInternal/CPUM/CMPXCHG16B 1
Use VirtualBox
Different networks
See diagrams on https://blogs.oracle.com/fatbloke/entry/networking_in_virtualbox1
- NAT
- Bridge
- Host Only: Host can access guest, but not the other direction. Outside cannot access guests. Good for running a test web server.
- Internal Network: Guests can access each other but host still cannot access guests. This is good for testing when you need a separate, clean network, and you can create sophisticated internal networks with vm's that provide their own services to the internal network. (e.g. Active Directory, DHCP, etc).
Internal Network
The Ip address for internal network is ipv6 (at least seen from Ubuntu guest machine).
inet6 addr: fe80::a00:27ff:fecb:966c/64
We can test it by pinging it from another machine (say Windows). Note that even it first shows Destination host unreachable, the 3 replies lines shows the pinging is successful.
C:\Users\brb>ping fe80::a00:27ff:fecb:966c
Pinging fe80::a00:27ff:fecb:966c with 32 bytes of data:
Destination host unreachable.
Reply from fe80::a00:27ff:fecb:966c: time=1ms
Reply from fe80::a00:27ff:fecb:966c: time<1ms
Reply from fe80::a00:27ff:fecb:966c: time<1ms
Ping statistics for fe80::a00:27ff:fecb:966c:
Packets: Sent = 4, Received = 3, Lost = 1 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 1ms, Average = 0ms
C:\Users\brb>netstat -rn
===========================================================================
Interface List
20...08 00 27 62 8c 1c ......Intel(R) PRO/1000 MT Desktop Adapter #2
11...08 00 27 86 6d 29 ......Intel(R) PRO/1000 MT Desktop Adapter
1...........................Software Loopback Interface 1
12...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
13...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
14...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.0.2.2 10.0.2.15 10
10.0.2.0 255.255.255.0 On-link 10.0.2.15 266
10.0.2.15 255.255.255.255 On-link 10.0.2.15 266
10.0.2.255 255.255.255.255 On-link 10.0.2.15 266
127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
169.254.0.0 255.255.0.0 On-link 169.254.200.31 266
169.254.200.31 255.255.255.255 On-link 169.254.200.31 266
169.254.255.255 255.255.255.255 On-link 169.254.200.31 266
224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
224.0.0.0 240.0.0.0 On-link 10.0.2.15 266
224.0.0.0 240.0.0.0 On-link 169.254.200.31 266
255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
255.255.255.255 255.255.255.255 On-link 10.0.2.15 266
255.255.255.255 255.255.255.255 On-link 169.254.200.31 266
===========================================================================
Persistent Routes:
None
IPv6 Route Table
===========================================================================
Active Routes:
If Metric Network Destination Gateway
1 306 ::1/128 On-link
11 266 fe80::/64 On-link
20 266 fe80::/64 On-link
20 266 fe80::28f6:df10:9926:c81f/128
On-link
11 266 fe80::48bc:2c38:765d:f88f/128
On-link
1 306 ff00::/8 On-link
11 266 ff00::/8 On-link
20 266 ff00::/8 On-link
===========================================================================
Persistent Routes:
None
Suppose we want to share some folder from host to guest. Assume in Virtualbox, we use "Downloads" as the folder name in Share Folders dialog.
Method 1: Use Auto-mount option built in VirtualBox. But I get a permission denied error. The reason is we have to add the current user to the group vboxsf.
sudo usermod -a -G vboxsf USERNAME # reboot is required # the shared folder is under /media/ with sf_ as prefix.
See http://www.cyberciti.biz/faq/howto-linux-add-user-to-group/ for more examples of using usermod command.
Howtogeek.com provides another way to add user to vboxsf.
sudo adduser USERNAME vboxsf
We can then use id USERNAME to verify you are in the vboxsf group.
Method 2: We can use the following method to get an access to Downloads folder for this session only. See also howtogeek.com.
sudo mkdir /mnt/Downloads sudo mount -t vboxsf Downloads /media/downloads
Method 3: We can use the following method for permanent solution.
sudo nano /etc/fstab sudo mkdir /mnt/Downloads # Add a new line # Downloads /mnt/Downloads/ vboxsf defaults 0 0 sudo mount -a
PS: There is a bug in virtualbox 4.3.10 which results an error
mount: wrong fs type, bad option, bad superblock on hostshare,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
The solution is to run
sudo rm /sbin/mount.vboxsf sudo ln -sf /usrs/lib/x86_64-linux-gnu/VBoxGuestAdditions/mount.vboxsf /sbin/mount.vboxsf
Windows guest machine + file sharing
In the File Explorer, one needs to check 'Turn on network discovery and file sharing' in order to use see the shared folder in the File Explorer (called File sharing in Windows). The shared folder is under Network > VBOXSVR directory.
Seamless mode
If we want to run the app from guest machine on host machine (to hide the guest machine desktop) so the app looks like from the host machine, we can head to View->Switch to Seamless Mode in VirtualBox.
Snapshots
If we are installing a sketchy program, we can take a snapshot, install the program, then revert to your snapshot if things go wrong.
http://www.howtogeek.com/150258/how-to-save-time-by-using-snapshots-in-virtualbox/
Create a snapshot
- Create a clean machine.
- There are two ways:
- (When the VM is off) Switch from 'Details' to 'Snapshots' on the right-hand side of the VB window. Right click 'Current State' and click 'Create Snapshot'.
- (When the VM is on) Machine > Take a snapshot. Give it an intuitive name and description. Shutdown the current machine (This seems to be a good practice every time after we create a VM).
After we open an original snapshot and do not nothing, when we shutdown the VM, the VM status is 'changed'.
Restore a snapshot
- Select the Virtual machine from the list and switch over to the snapshots view (top-right corner). Right click a snapshot and choose 'Restore snapshot'. Uncheck the option of 'Create a snapshot of the current machine state'. Click 'Restore'.
- You should see the "Current State(changed)" will become "Current State" the same as the snapshot you selected to restore to.
- If we have a snapshot called original at the top, and a child snapshot, then running restore a snapshot on the root will move the "Current State" from under the child snapshot to the root snapshot. That is we have two children snapshots now (one of them is 'Current State').
Note that
- There is only one 'Current State' no matter how many snapshots we have created.
- If we stop the mouse at any snapshot and double click to run the VM, it still pick the 'Current State' to run. The title bar on the virtual machine will show which snapshot it is running.
- When we right click 'Restore snapshot' and choose 'Create a snapshot of the current machine', it will create a snapshot under the image we have selected. See the next plot
- If we run the VM on snapshot1 and use apt-get to install eg gfortran package, the current state will be changed. Now if we shutdown the machine and right click 'Restore snapshot' & check 'Create a snapshot of the current machine state'. A snapshot named 'Snapshot 2' will be created nested under 'Snapshot 1'.
- Again if we run the VM (may be through right click 'Restore Snapshot' if we want to run the VM based on a specific snapshot), the title bar on the virtual machine will show which snapshot it is based on. For example, if the Current State is nested under 'Snapshot 1', then the image is based on 'Snapshot 1'.
- If we do not try to take snapshot on 'Current State', anything we have done on a 'Current State' based on whatever snapshot could be lost after the VM is shutdown.
Clone
It will give an option of 'Full Clone' and 'Linked clone'. After that, it will give an option to choose which parts of the snapshot tree should be cloned with the machine: 'Current machine state' and 'Everything'.
See the screenshots.
Take a screenshot
- Method 1. Use 'snipping tool' in Windows 7 to make a screenshot of a desired region to a clipboard. When the 'New' button is clicked, the whole Windows desktop will be less clear. Users can use the mouse to select a region. When we select a rectangle region, the region will become clear. After we release the mouse, the region will be shown on the snipping tool application. In fact, the region will also be on Windows clipboard. So if the VirtualBox has enabled shared clipboard for both directions, we can access the clipboard on Ubuntu host OS.
- Method 2. Use the command line in the host machine to take a screenshot of the whole guest OS. See http://www.dedoimedo.com/computers/virtualbox-screenshot.html
VBoxManage controlvm <VM_NAME> screenshotpng <FILENAME>
To copy the image to the clipboard, I open the file in gthumb program. Then using Edit -> Copy the image to copy the image to the clipboard. If I leave the gthumb program open, it will update the image when I use the same file name to make a new screenshot on the command line.
- Method 3. Use the keyboard short Host + E in the VirtualBox. It will ask a file name to save the screenshot. Not that convenient if my purpose is to copy the image to the clipboard.
Port forward
If you’d like to run server software inside a virtual machine, you’ll probably want to set up port forwarding so the server software is reachable from outside of the virtual machine. You’ll find this option in the Network settings pane, under Advanced.
If we change to use the 'Bridged' network, we don't need to use port forward. We use 'port forward' if we use the default 'NAT' network.
http://www.howtogeek.com/122641/how-to-forward-ports-to-a-virtual-machine-and-use-it-as-a-server/
Increase the guest machine space
- http://www.dedoimedo.com/computers/virtualbox-shrink-expand-disks.html
- http://www.howtogeek.com/124622/how-to-enlarge-a-virtual-machines-disk-in-virtualbox-or-vmware/
Boot virtual machines from USB drives
http://www.howtogeek.com/187721/how-to-boot-from-a-usb-drive-in-virtualbox/
Clone vs Import/Export appliance
Clone will create a new VM directory (including *.vdi) on the same machine.
Import/Export appliance (*.ova) allows to transport the appliance to a new machine.
- The appliance will not be touched on the new machine.
- The storage space cannot be adjust when we import an appliance.
- The .ova file can be opened in VMware Play.
Start virtual machine when the system boots up
Windows guest machine screen resolution
The available selection of the display resolution:
- 1600 x 1200 (win10)
- 1280 x 1024 (win10)
- 1152 x 864
- 1024 x 768
- 800 x 600 (win7)
Manage virtual machines
VBoxManage
vagrant
- http://en.wikipedia.org/wiki/Vagrant_(software)
- http://www.vagrantbox.es/ubuntu
- If we want to use Vagrant + vmware, we need to pay money. And it only works on Vmware workstation not Vmware player.
Vagrant boxes
Why vagrant
Vagrant provides easy to configure, reproducible, and portable work environments built on top of industry-standard technology and controlled by a single consistent workflow to help maximize the productivity and flexibility of you and your team.
To achieve its magic, Vagrant stands on the shoulders of giants. Machines are provisioned on top of VirtualBox, VMware, AWS, or any other provider. Then, industry-standard provisioning tools such as shell scripts, Chef, or Puppet, can be used to automatically install and configure software on the machine.
Tested on an Ubuntu host machine
$ sudo dpkg --install vagrant_1.7.1_x86_64.deb
[sudo] password for mli:
Selecting previously unselected package vagrant.
(Reading database ... 209831 files and directories currently installed.)
Unpacking vagrant (from vagrant_1.7.1_x86_64.deb) ...
$ vagrant init hashicorp/precise32 # No 'sudo' is needed
A `Vagrantfile` has been placed in this directory. You are now
ready to `vagrant up` your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
`vagrantup.com` for more information on using Vagrant.
$ cat Vagrantfile
$ vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Box 'hashicorp/precise32' could not be found. Attempting to find and install...
default: Box Provider: virtualbox
default: Box Version: >= 0
==> default: Loading metadata for box 'hashicorp/precise32'
default: URL: https://atlas.hashicorp.com/hashicorp/precise32
==> default: Adding box 'hashicorp/precise32' (v1.0.0) for provider: virtualbox
default: Downloading: https://atlas.hashicorp.com/hashicorp/boxes/precise32/versions/1.0.0/providers/virtualbox.box
==> default: Successfully added box 'hashicorp/precise32' (v1.0.0) for 'virtualbox'!
==> default: Importing base box 'hashicorp/precise32'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'hashicorp/precise32' is up to date...
==> default: Setting the name of the VM: Downloads_default_1420231386363_57276
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
default: Adapter 1: nat
==> default: Forwarding ports...
default: 22 => 2222 (adapter 1)
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
default: SSH address: 127.0.0.1:2222
default: SSH username: vagrant
default: SSH auth method: private key
default: Warning: Connection timeout. Retrying...
default:
default: Vagrant insecure key detected. Vagrant will automatically replace
default: this with a newly generated keypair for better security.
default:
default: Inserting generated public key within guest...
default: Removing insecure key from the guest if its present...
default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
default: The guest additions on this VM do not match the installed version of
default: VirtualBox! In most cases this is fine, but in rare cases it can
default: prevent things such as shared folders from working properly. If you see
default: shared folder errors, please make sure the guest additions within the
default: virtual machine match the version of VirtualBox you have installed on
default: your host and reload your VM.
default:
default: Guest Additions Version: 4.2.0
default: VirtualBox Version: 4.3
==> default: Mounting shared folders...
default: /vagrant => /home/mli/Downloads
$ vagrant destroy
More
$ vagrant box add ubuntu/trusty64 $ vagrant up $ vagrant ssh $ vagrant destroy $$ ls /vagrant # Web server $ nano bootstrap.sh $ nano Vagrantfile # add provision $ vagrant --provision $ vagrant ssh $ nano Vagrantfile # add port forward $ vagrant reload # Share $ vagrant login $ vagrant share Ctrl + C # Teardown $ vagrant suspend $ vagrant halt $ vagrant destroy # Provider $ vagrant up --provider=vmware_fusion
Install on a Windows machine
Note: If we want to use Vagrant with Virtualbox, we need to install Virtualbox separately. Vagrant does not include Virtualbox in its installer. Vagrant's installer (~150MB) only installs itself.
Go to the Download page to download Windows version (no separate 32 or 64-bit versions). The program will be installed onto C:\HashiCorp directory.
I can install Virtualbox and Vagrant on a virtual Windows 7 guest machine. This is a great advantage of vagrant over docker in that I cannot run (installation is fine) dock2boot on a Windows 7 guest machine (Docker requires a real Windows to work). But it is perfect OK to install and run docker on an Ubuntu guest machine.
After installing virtualbox & vagrant, vagrant will be available on a global environment. That said, we can open a command window and start to run 'vagrant'.
C:\Users\brb>vagrant init hashicorp/precise32
A `Vagrantfile` has been placed in this directory. You are now
ready to `vagrant up` your first virtual environment! Please read
the comments in the Vagrantfile as well as documentation on
`vagrantup.com` for more information on using Vagrant.
C:\Users\brb>vagrant up
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Importing base box 'hashicorp/precise32'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'hashicorp/precise32' is up to date...
==> default: Setting the name of the VM: brb_default_1421961025717_91472
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
...
default: Guest Additions Version: 4.2.0
default: VirtualBox Version: 4.3
==> default: Mounting shared folders...
default: /vagrant => C:/Users/brb
C:\Users\brb>
C:\Users\brb>vagrant ssh
`ssh` executable not found in any directories in the %PATH% variable. Is an
SSH client installed? Try installing Cygwin, MinGW or Git, all of which
contain an SSH client. Or use your favorite SSH client with the following
authentication information shown below:
Host: 127.0.0.1
Port: 2222
Username: vagrant
Private key: C:/Users/brb/.vagrant/machines/default/virtualbox/private_key
C:\Users\brb>
The next step is to use Putty to connect to the virtual machine. We can follow the instruction at https://github.com/Varying-Vagrant-Vagrants/VVV/wiki/Connect-to-Your-Vagrant-Virtual-Machine-with-PuTTY. However, the private key used for conversion is not the one as described in the article. We should uses the private key indicated in the above message (C:/Users/brb/.vagrant/machines/default/virtualbox/private_key in this case).
Note that when we run 'vagrant up', we will see a new VM was created in VirtualBox and once we run 'vagrant destroy', the VM will be deleted.
If we run 'vagrant destroy' and then 'vagrant up' again, the old private key will not work in the new guest machine.
Sharing a Windows/host folder in Vagrant vm
See the tutorial video on youtube. In this example, an apache is created in vm. The goal is to install Apache in the vm and use a folder on Windows/host system as the DocumentRoot.
First we edit Vagrantfile, uncomment 'config.vm.network' line, and modify ip as anything you want. After we modify Vagrantfile, we can issue 'vagrant reload' to make the change effective immediately.
Now use 'vagrant ssh' to ssh to the vm and install apache2, ... and start apache2.
The interesting thing is if we create a new subfolder (/vagrant/www) in the vm, this folder will appear in the Windows/host system as well. If we change /etc/apache2/sites-available/default file AND modify DocumentRoot to /vagrant/www, <Directory> to /vagrant/www, and AllowOverwrite to None, we will be able to use the www subdirectory from the Windows/host system as the DocumentRoot for the Apache in the vm.
Use vagrant with Docker (instead of VirtualBox) provider
Use vagrant to run a VM remote desktop with desktop environment
How to setup a LAMP/Web Stack development environment
- https://www.howtoforge.com/tutorial/vagrant-ubuntu-linux-apache-mysql-php-lamp/ (I tested it)
- http://www.dev-metal.com/super-simple-vagrant-lamp-stack-bootstrap-installable-one-command/
- https://box.scotch.io/
However, I got an error complaining password in the configuration. See this post for help. A simple way to get rid of the error is to comment out the username and password lines.
The post tells us 1) how to create a lamp server using Vagrantfile and a shell script, 2) how to save the box for future use.
The <Vagrantfile> file looks like
Vagrant.configure(2) do |config|
config.vm.box = "precise32"
# Mentioning the SSH Username/Password:
# config.ssh.username = "vagrant"
# config.ssh.password = "vagrant"
# Begin Configuring
config.vm.define "lamp" do|lamp|
lamp.vm.hostname = "lamp" # Setting up hostname
lamp.vm.network "private_network", ip: "192.168.205.10" # Setting up machine's IP Address
lamp.vm.provision :shell, path: "script.sh" # Provisioning with script.sh
end
end
and the <script.sh> file looks like
#!/bin/bash # Updating repository sudo apt-get -y update # Installing Apache sudo apt-get -y install apache2 # Installing MySQL and it's dependencies. # Also, setting up root password for MySQL as it will prompt to enter the password during installation sudo debconf-set-selections <<< 'mysql-server-5.5 mysql-server/root_password password rootpass' sudo debconf-set-selections <<< 'mysql-server-5.5 mysql-server/root_password_again password rootpass' sudo apt-get -y install mysql-server libapache2-mod-auth-mysql php5-mysql # Installing PHP and it's dependencies sudo apt-get -y install php5 libapache2-mod-php5 php5-mcrypt
We can verify the apache is working by browsing the address http://192.168.205.10. Note that the host-only network IPv4 address is 192.168.205.1 (not sure if this is coincidence).
Headless VirtualBox with phpvirtualbox
For some reason, I got an error 'Could not connect to host (127.0.0.1:18083)'. A solution is to restart it. See this wiki from sourceforget.net.
sudo /etc/init.d/vboxweb-service stop sudo /etc/init.d/vboxweb-service start
Other visualization software
Hypervisor/Virtual machine monitor
Hypervisor from wikipedia.
- Type 1: native or bare-metal hypervisors. These hypervisors run directly on the host's hardware to control the hardware and to manage guest operating systems. Examples include Oracle VM Server for SPARC, Oracle VM Server for x86, the Citrix XenServer / XenClient, VMware ESX/ESXi and Microsoft Hyper-V 2008/2012.
- Type 2: hosted hypervisors. These hypervisors run on a conventional operating system just as other computer programs do. Type-2 hypervisors abstract guest operating systems from the host operating system. VMware Workstation and VirtualBox are examples of type-2 hypervisors.
VMware
apt-get update apt-get install build-essential module-assistant m-a prepare cd Downloads tar xzvf /media/cdrom0/VMwareTools-9.2.0-799703.tar.gz cd vmware-tools-distrib ./vmware-install.pl [Accept all default] shutdown -r now
Convert between vmdk and ova format
See this article in howtogeek.com
vSphere
This is a type 1 hypervisor.
oVirt
Emulation vs virtualization
Virtualization allows users to configure virtual machines outfitted with similar hardware and processors as the host system, whereas emulation simulates different hardware and processor configurations in software.
Emulators are what allow you to run old Commodore 64 or NES games on a PC, for example.