<h3class="subsectiontitle">Installing VirtualBox on Windows</h3>
<p>I already have this installed and I have been using it for several years so I’m not too concerned about this section, but I recently installed it on a new PC and I didn’t install the extension pack so I will do that now and document the process.</p>
<p>First of all, the extension pack provides a lot of additional features including</p>
<preclass="inset">
• Support for USB 3.0 devices
• Support for the Remote Desktop Protocol (VRDP)
• Intel PXE boot ROM (?)
• Disk image encryption (AES)</pre>
<p>The extension pack can be downloaded from <ahref="https://www.virtualbox.org/wiki/Downloads">Oracle</a>. Look for the extension pack and click the link labelled 'All supported platforms'. When it is downloaded, you can select Open if you have that option or you can just locate the file and double click it to run it.</p>
<p>This installation method seems to be based on the assumption that you have installed the latest version of Virtual Box. When I tried this, I got an error and it looked as though installation had aborted. I updated Virtual Box to the latest version and ran it again and I saw a message stating that the extension pack was already installed.</p>
<p>It gives you the option to reinstall and I did that. This time I got a confirmation that the pack had installed successfully.</p>
<p>It may be worth noting that this is being installed on Virtual Box, you don't install it on individual VMs.</p>
<h2class="sectiontitle">Manage VirtualBox with the GUI</h2>
<p>Preferences for Virtual Box are under the File menu. For instance, if we select File > Preferences and then select Input in the left-hand pane, we will see the following dialog.</p>
<p>There are two tabs here, VirtualBox Manager and Virtual Machine with the former interacting with the Virtual Box manager rather than a specific VM and the latter interacting with the VM. If we select the Virtual Machine tab, the first entry is the Host Key Combination (which defaults to the Right Control key on Windows. Other options expand on this so for instance, the option for full screen is given as Host + F and so this means that we use the Right Control key + F. Another useful shortcut is the Host + Delete which is, on the VM, the equivalent of pressing Control+Alt+Delete.</p>
<p>There are also two options which may seem to be quite similar, Take Screenshot (Host+E) and Take Snapshot (Host + T). Take Screenshot is exactly what you would expect but in this context, a snapshot refers to a snapshot of the machines current state so the purpose of this option is to save the current state of the machine. I guess this means, for instance, if you install something that causes conflicts, rather than uninstalling it you can revert to an earlier machine state.</p>
<p>Under the Machine menu we have several useful options including New which creates a new VM, Settings to change the settings for that VM, Clone to clone that VM and remove to remove that VM. Note that if a VM is removed, you have the option of keeping its hard drives which you may want to do if you intend to attach these to a new VM.</p>
<p>We mentioned earlier that CentOS is based on RedHat Enterprise Linux and in fact, RHEL is the upstream distribution for CentOS. This means that when a new version of RHEL is released, a new version of CentOS is released shortly after and the CentOS version number is a reflection of the version of RHEL it is based on. For instance, for RHEL 7.2, the corresponding version of CentOS might be CentOS 7.2.-1511 (where 1511 is a reference to the release date, in this case November 2015).</p>
<p>Minor upgrades to the OS can be done in place (via a Terminal) but upgrading between major versions requires a reinstall. As is typical, the version number represents a major and a minor version number with, in the example given here, 7 being the major version and 2 the minor.</p>
<p>CentOS can be installed from DVD or a full ISO image (about 4.3GB). There is also a smaller image which is about 380MB and this is used for a network install so it requires a fast broadband connection and even with this proviso, is much slower than installing from a full image.</p>
<p>Note that CentOS only supports 64-bit Intel and AMD processors but there are community-developed versions supporting other processors including Arm, PowerPC and Intel/AMD 32 bit.</p>
