When you think of virtualization, bare-metal hypervisors such as VMware ESX and ESXi, Microsoft Hyper-V and Citrix XenServer come to mind. But hosted virtualization is a whole different ballgame.
Hosted virtualization requires you to install an operating system before deploying the hypervisor, meaning the hypervisor doesn’t have direct access to hardware resources. These kinds of hypervisors are often cheaper than bare-metal, so they’re well-suited for small data centers or test and development environments. In a lab, hosted virtualization can help you test OS compatibility and applications.
This guide covers the different hosted hypervisor options and how to deploy hosted virtualization in your infrastructure.
When you decide to virtualize, you have to choose between bare-metal and hosted virtualization hypervisors, so it’s important to understand the differences. Compare costs, performance and vendor choices for each hypervisor before you decide to go hosted. Hosted virtualization is different than bare-metal from the moment of installation.
Defining Type 2 hypervisors
Hosted virtualization hypervisors are also known as Type 2 hypervisors. Installed above the host OS, these hypervisors coordinate resource usage in the virtual environment through the OS. Benefits of hosted hypervisors include hardware and driver compatibility, flexibility with the configuration and integration of familiar management tools.
Some security issues can arise, however, since the OS is directly involved in virtual infrastructure management, rather than just the hypervisor itself. Plus, not all virtualization platforms are so easily defined; hypervisors such as the Kernel-based Virtual Machine show characteristics of both bare-metal and hosted virtualization hypervisors.
Hosted virtualization vs. bare-metal virtualization
Since a hosted hypervisor requires you to first install an OS, it’s similar to an application. Because the OS is responsible for the hardware drivers, hosted virtualization allows for better hardware compatibility. Then again, accessing the hardware through the OS can increase resource overhead and decrease virtual machine (VM) performance. Hosted virtualization hypervisors are common for desktops and test environments because of this performance overhead.
Aside from its ESX and ESXi bare-metal virtualization, VMware offers a few hosted virtualization options. VMware Workstation is often used for desktops and laptops in personal labs or test environments. The latest version, VMware Workstation 8, offers many of the same capabilities as bare-metal virtualization, allowing you to emulate a production infrastructure.
Another hosted virtualization option, VMware Player, is a free tool with a small resource footprint that’s good for virtualization first-timers, and VMware Fusion extends virtualization to Mac OS users.
Upgrading to VMware Workstation 8
VMware Workstation 8 includes support for 64-bit OSes, integration with vSphere and a well-organized new interface. Upgrading to Workstation 8 is fairly easy, as long as you follow the hardware requirements and installation instructions. With the new features, you can nest 64-bit VMs in vSphere inside Workstation, and drag and drop VMs from the test environment into production. The new interface also makes it easier to monitor VMs, mark favorites and control more VM functions.
VMware Workstation security best practices
Host virtualization hypervisors tend to be less secure than bare-metal hypervisors because they do not directly access the hardware. You can boost VMware Workstation security by shutting down unnecessary VMs and patching regularly. Determine which VMs, appliances or applications are your most critical, and protect those first and foremost. You should also configure the network to restrict visibility into certain VMs or hosts, and configure appropriate firewalls.
Bringing Workstation test VMs into production
VMware’s hosted virtualization platform helps you test VMs in a non-critical environment, but you may eventually want to move some into your production infrastructure. In VMware Workstation 8, it’s easy to connect to ESXi hosts and copy VMs to production. A copy of the VM remains in the Workstation environment, but you have to perform all management tasks through the vSphere Client. Copying VMs to ESXi production hosts helps you capitalize on your Workstation testing.
Using VMware Player for hosted virtualization
VMware Player is the company’s most basic platform, a free hosted virtualization tool for virtualization beginners. It’s simple to use in test environments, but isn’t great for production since VMware Player is not very customizable. Still, even admins with complex production infrastructures find Player useful for running multiple OSes on any computer.
VMware also offers Fusion for Mac, a very similar hosted virtualization platform to Workstation. VMware Fusion allows Mac users to run multiple OSes on one machine, particularly in test environments. Parallels Desktop for Mac is another hosted virtualization product that allows users to run a virtualized Windows OS on a Mac computer.
VMware Fusion performance tips for Mac users
You may encounter performance issues with VMware Fusion if you run too many guests at once. For the best VMware Fusion performance, you need as much RAM as possible and Mac OS X 10.5 or higher. If you’re a power user, it’s a good idea to get an external hard drive. To monitor different OSes, you can enable the Spaces feature in OS X and easily flip back and forth between VMs.
Advanced VMware Fusion tips for power users
For even better performance, advanced VMware Fusion users should try disabling graphics-intensive components in the OS, such as the Aero interface. Also, make sure you’re using the best OS for your applications. Some apps require a 64-bit OS, but others may still work better on 32-bit. And for I/O performance, some users find that SCSI hard disks are your best bet. Lastly, it’s a good idea to defragment your VM drives at least once a month.
Nesting VMs in VMware Fusion and Workstation
In VMware Fusion and Workstation, you can run a hypervisor inside the testing platform, then run a VM inside that hypervisor. Nesting VMs is useful for testing different hypervisors in your infrastructure. You could even run Microsoft Hyper-V inside Fusion or Workstation to test VMs on that platform. The possibilities are endless, and VMware Fusion 4 and Workstation 8 now support 64-bit nested VMs.
Parallels Desktop through a VMware Fusion user’s eyes
Parallels Desktop for Mac is a similar hosted virtualization product to VMware Fusion, allowing users to run virtualized OSes on their Mac computers. But in Parallels Desktop, it’s simpler to configure the virtual networks without scripts. Some users also find the VM encryption in Parallels’ product useful, and Parallels Desktop for Mac even shows your VMs’ applications in the main dock.
Oracle’s hosted virtualization platform is Oracle VM VirtualBox. The product is free and open source, and it’s similar to VMware’s hosted virtualization offerings. VirtualBox is commonly used in test environments, for isolation or disaster recovery purposes, and in small infrastructures on a budget.
Oracle VM VirtualBox 4 overview
Some of Oracle VM VirtualBox’s notable features include: multi-generation branched snapshots; built-in support for connecting to iSCSI storage devices; support for up to 32 virtual CPUs per VM; and teleportation for running VMs. Oracle VM VirtualBox also provides a command-line utility that allows you to mimic the functionality of the local management GUI in a PowerShell-like environment. This host virtualization product offers many comparable features to Hyper-V and VMware.
Oracle VM VirtualBox vs. VMware Workstation
There are major differences between VMware Workstation and VirtualBox. Workstation offers integration with other VMware products, but Oracle VM VirtualBox is free. It also provides teleportation, which is similar to VMware vMotion and Hyper-V Live Migration. Oracle VM VirtualBox also supports more OSes than VMware Workstation. But Workstation has cool features of its own: AVI recording and screen capturing, VM teaming features, and the ability to create a memory dump of a VM.
Creating VMs with Oracle VM VirtualBox 4
If you decide to use Oracle VM VirtualBox for hosted virtualization, the first step is to create VirtualBox VMs. The VirtualBox Manager will launch a wizard to guide you through the process. You basically have to name the VM, choose the guest OS, configure resource settings and install the guest OS. Then, you can edit the VM’s hardware settings, modify the number of CPUs and configure network interface cards. Once that’s done, you’re ready to use Oracle VM VirtualBox in a small environment or test lab.
Dig Deeper on Virtualized test and development environments