Windows Server 2008 : Using Virtualization to Increase Productivity and Facilitate Consolidation - Installing Hyper-V

1. Understanding Virtualized Machine Components

Whenever a new virtual machine is created, some necessary hardware components are allocated through the use of software emulation. Think about it. Whenever you use an individualized operating system, it has to access its own hard drive, network card, and system memory. Some of these components are vital for operation. Say, for instance, you're running an instance of SUSE Linux, and you're going to be using this instance of Linux to run a website that takes advantage of PHP Hypertext Preprocessor (PHP). To do this, you'd need to have an individual installation that had its own network settings, memory, and disk. Imagine for a moment that this is a medium-traffic web server. The I/O operations alone would be difficult for a single server to hold, but since this is a consolidated and "hypervised" (monitored by Hyper-V) system, it's even harder to maintain.

A lot of the reason behind this is that although there may be two operating systems running two of every single operating component, on most low-end, low-cost servers there is only one memory bus, or one memory card, and maybe even one RAID configuration. And that isn't likely to change. Thus, the hypervisor has the task of determining where the resources are allocated. At times, this can be very complicated.

Thankfully, most of what the hypervisor does has been automated to a point that it doesn't require much administrative work on the part of the lowly administrator who has been tasked with designing a consolidated server role. Really, using Hyper-V is as simple as opening up the virtualization management console (VMC).

1.1. Using the Virtualization Management Console

The VMC in Windows Server 2008 is called the Hyper-V Manager. Using the Hyper-V Manager, you're allowed access to the central brains of the hypervised machines. Here, you can create new virtualized machines, take snapshots, manage the licensing, and alter the hardware settings discussed earlier. You can access the VMC by selecting Start => Administrative Tools => Hyper-V Manager.

1.2. Snapshots

If you've used Windows XP or Windows Vista, a snapshot is pretty easy to understand. In a way, it's similar to a system restore. A VM snapshot gives you the ability to take a "photo" at a certain time of the condition of that virtualized operating system. The mother operating system (Windows Server 2008 when using Hyper-V) has the virtual machine record a data list of all its settings that will allow you to roll back to the previously established settings within Hyper-V at any point. So, if for some reason your virtual machine stops working, you can revert to a snapshot and continue working unimpeded as if nothing ever happened. Of course, any changes made after the snapshot will be lost. But part of the real advantage of snapshots is that you can decide where you want to place them on the system. This is useful if you want to deposit a snapshot on an external resource, such as a networked drive or external hard drive, for recovery purposes.

1.3. Failover and Recovery with Hyper-V

One of the primary objectives of Hyper-V is, surprisingly, disaster recovery. When you first think about it, this may not make a lot of sense. At first glance, Hyper-V is just virtualization software that allows the really nifty deployment of other platforms. However, there's more to it than that. Using Hyper-V and snapshots, administrators are able to take entire installations and store them at a given point and time.

Logically, this means that these snapshots are available for recovery. Thus, failover recovery is quite easy. And furthermore, in the case of an upgrade or move, the process of migration is greatly simplified because downtime is almost entirely removed. But the final advantage of Hyper-V is that it also supports Volume Shadow Copy.

2. Network Setups with All Types of Virtual Machines

When a virtual machine is initially created, you can set it up in several ways. But of particular concern to most any administrator is the method that allows you to possibly use a single network card for multiple computers. In sharing the Ethernet port, you have three available options: using the host's NAT, using a bridged connection, and allowing only a network with the host.

2.1. Host NAT

Using host NAT, the host actually creates a virtualized DHCP pool and assigns an IP address to the virtual machine running in it. This is ideal for a machine that won't have to be communicated with but will communicate with machines outside the network. The reason behind this is that NAT, by its very nature , serves as an internal firewall. It's kind of funny, but by installing a virtual machine and using host NAT, you are effectively setting up a machine within a software firewall.

This said, the machine can still reach out and access the Internet, send email, and do the tasks it needs to perform in order to function (most of the time). Problems start to arise only when you want to use this server for, say, a web server or for a platform such as Microsoft Exchange. This is relatively difficult, if not impossible, because NAT doesn't play well with others.

2.2. Bridged Connection

A bridged connection is by far the best method if it's available. Using a bridged connection, the VM creates its own unique IP address and authenticates to the network as if it is something completely separate. It can be a pretty surreal feeling to look at two distinct machines on one computer, each with their own network card. It still makes many of us say, "Huh. . .well, that's something." Not only does the virtual machine function on the same network, but outside resources from your network can individually access the logical address of that virtual machine and have no idea that it isn't really a whole other entity. To them, it just looks like another host.

2.3. Host Only

The least desirable method of connection is to allow connection only with the host. This creates an environment where VMs cannot communicate with the outside world and can run only in the virtual environment. Sometimes, this can be useful if you'd like to test a software program in a secure environment, because the two OS installations can still communicate. But it has little other practical use and is thus less common.

3. Virtual Networks

Now that you understand how network cards can be physically shared through software implementation (try getting your head around that for a minute!), let's talk a little bit about virtual networks and the role they play within Windows Server 2008 Hyper-V installations.

When you first set up a Hyper-V installation, you have the option of creating special types of virtual networks. In total, there are three types: internal virtual networks, external virtual networks, and private virtual networks.

Using a virtual network, Windows Server 2008 Hyper-V can isolate communication types with child machines. In the following sections, I'll discuss in detail each type of network you can create.

3.1. Internal Virtual Networks

The primary use of an internal virtual network is testing. Using an internal network, an administrator can create a network that will communicate between the child virtual server and the parent host server. This is convenient if you need to test applications because it isolates the communication that will be done within the virtual network. This enables the following types of communication:

• Virtual machine to virtual machine within the same physical server

• Virtual machine to parent host server

3.2. External Virtual Networks

The word external in external virtual network implies that the network is not necessarily a network outside the virtual server but nevertheless can be accessed externally. This means that users outside of the area you define within your network can access the virtual server through its own unique IP address. This enables the following types of communication:

• Virtual child machine to virtual child machine

• Virtual child machine to parent

• Virtual child machine to outside world

3.3. Private Virtual Networks

A private virtual network is created when you want two virtual machines to communicate but it's imperative that they be able to communicate only with one another. Usually, this is done for testing. For example, imagine you have an application that needs two servers to run. Instead of getting two separate computers and then installing operating systems on them both, you can create two virtual machines and give them a private network to communicate to each other. This enables the following type of communication: virtual machine to virtual machine.

4. Multiple Network Interface Cards with Virtual Networks

The already-common practice technique of using multiple network interface cards (NICs) for different missions will be used even more in the future of Hyper-V. Generally, the Microsoft documentation strongly encourages the use of several Ethernet adapters because there are three distinct needs in a virtualized operating environment:

• The host OS (Windows Server 2008) requires a port.

• The virtualized environment should have a dedicated port.

• The iSCSI array (which is recommended) should have a dedicated port.

As you can see, the need for a large amount of network connectivity grows extremely quickly. Fortunately, Microsoft Windows Server 2008 supports a large number of NICs already, including NICs that have onboard packet management and other useful tools.

5. Installing Hyper-V

In the following exercises, you will apply what you have learned in the preceding sections by installing Hyper-V. To complete Exercise 1, you must have a computer that supports at least Windows Server 2008 Standard edition and either AMD-V or Intel VT. You will not be able to get past the first step of Exercise 1 if you do not have that hardware. In addition, please note that these exercises build on one another, so you will need to do them in the sequence presented here.

In the next exercise, you will proceed with the installation of Hyper-V. You must have completed Exercise 1 in order to do Exercise 2.

Exercise 2: Installing Hyper-V The install process for Hyper-V begins like most any server role install with Windows Server 2008. First click the Server Manager button, and then select Add Roles => Hyper-V. At this point, if you do not meet the hardware requirements, you will be greeted with the warning shown here. Otherwise, you will be able to select the Hyper-V check box, as shown here. Click Next. On the next screen, you can select a network card for use in your virtual network. In the example shown here, only one network card is available, so you will choose that one. However, if you have multiple network cards and don't select one, they would not be set up as virtual networks. The install will continue, as shown here, after you click Next. Once you've completed the install process, you will be prompted to close the installer and reboot, as shown here. Upon reboot, the resume installer will begin. When complete, you'll be presented with a summary screen. Click Close.

In Exercise 3, you will set up Hyper-V. To complete this exercise, you must have completed Exercises 1 and 2.

Exercise 3: Setting Up Hyper-V To begin setting up Hyper-V, select Start => Administrative Tools => Hyper-V Manager. This opens the Hyper-V Manager home screen shown here. In the Hyper-V Manager, select the name of your computer, and in the upper-right portion of the screen, select New Virtual Machine, as shown here. On the initial configuration screen, if it's shown, click Next. On the Specify Name and Location screen, name the virtual machine something appropriate, such as SUSE Linux. Click Next. On the Assign Memory screen, you can pick the amount of memory to be assigned to this virtual machine. Keep in mind that this is limited by the amount of memory you possess. For our purposes, 512MB should suffice. Place this (if available) in your box, and click Next. When the Configure Networking screen appears, you can select from the drop-down menu any virtual networks that have been created in this or any previous installs. Otherwise, there will be no virtual networks. Click Next when complete. On the next screen, Connect Virtual Hard Disk, you can choose to either create a new hard disk or work from a preexisting virtual disk. In this exercise, you will create a new disk and assign 15GB. Click Next when complete. You will install an operating system later, so select Install Operating System Later, and click Next. When the screen shown here appears and the Finish button is available, make sure you select the check box to start the virtual machine upon exiting the wizard.

In Exercise 4, you will install an operating system on a preexisting virtual machine. You must have completed Exercises 1 to 3 to do this exercise.

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