Virtualisation, for the uninitiated, describes the use of software to provide a complete, functional simulation of a hardware environment. Data can be stored, programmes can be run and memory can be managed exactly as if the virtual machine were an actual computer. Nowadays, this is very much an accepted part of business IT.
To understand the benefits in a little more depth, imagine that your company runs half a dozen servers at around 15 per cent utilisation. Virtualisation would allow you to consolidate this infrastructure in one hardware environment without compromising performance, as well as to reduce the time and money you’d normally spend adding new hardware to the mix.
However, before you can virtualise, you need to get yourself a hypervisor. In simple terms, this is the system that creates and runs those virtual machines. It’s responsible for making sure that they act like real computers, are straightforward to manage and support, and offer an acceptable level of stability for business use.
In the early days of virtualisation, VMware was considered the undisputed king of hypervisors. Nowadays, however, there are a number of alternatives on the market – notably Microsoft Hyper-V, Citrix XenServer and Oracle VM – that are arguably now as proficient and reliable as their more mature forebear. This means that if you intend to take your business down the virtualisation route, there’s no shortage of options to consider.
So, how do you choose a hypervisor? Do you need to pay through the nose for the industry standard, or will an open-source solution do the trick? And should you pay attention to the growing hubbub about the market becoming commoditised?
Here are five things to consider before you set up your first virtual environment.
Type 1 v Type 2 hypervisors
The first thing you need to know about hypervisors is that they come in two distinct flavours, originally defined by computer scientists Gerald J Popek and Robert P Goldberg in Formal requirements for virtualizable third-generation architectures:
- Type 1, or ‘bare metal’, hypervisors. As the name suggests, these run directly on your hardware – there’s no operating system acting as an intermediary, making them the fastest option out there.
- Type 2, or hosted, hypervisors. In contrast to their bare-metal counterparts, these run like regular computer programmes on a conventional operating system such as Windows or Linux.
Type 1 hypervisors offer much better performance than Type 2 ones because there’s no middle layer, making them the logical choice for mission-critical applications and workloads. But that’s not to say that hosted hypervisors don’t have their place – they’re much simpler to set up, so they’re a good bet if, say, you need to deploy a test environment quickly.
The cost of a hypervisor
For many buyers, the toughest part of choosing a hypervisor is striking the right balance between cost and functionality. While a number of entry-level solutions are free, or practically free, the prices at the opposite end of the market can be staggering. Licensing frameworks also vary, so it’s important to be aware of exactly what you’re getting for your money.
At this point, it’s also worth thinking about whether or not you should stick to one vendor or use several. Different hypervisors offer different sets of management tools and advanced features, so it can be tricky to stay in control when you’ve got dozens of solutions running at once. However, it might also be untenable to use a premium hypervisor for non-critical applications. Consider a tiered approach that matches price point to workload.
How the solution performs
As mentioned above, there’s strong sentiment in some technology circles that as the market matures, virtualisation is becoming commoditised. For now, though, buyers mustn’t ignore the fact that a hypervisor is a complex piece of kit, and that hardware performance, memory management and stability do indeed vary from one solution to the next. As such, you should consider what’s more important to the workload in question: high availability, for example, or the ability to squeeze every last drop out of your physical CPU and RAM?
Note also that recovering lost data from virtual environments presents a range of unique problems and challenges, so be sure that your choice of hypervisor won’t hurt your chances of saving mission-critical files and folders from catastrophe.
The availability of management tools
Choosing a hypervisor also involves working out whether or not you’re going to want to be hands-on when it comes to managing your virtual machines. Some solutions have better management tools and utilities than others, both in terms of out-of-the-box software and optional add-ons from third-party developers. As the most mature hypervisor on the market, VMware is often felt to offer the strongest suite of management tools. Other vendors are catching up, but not all at the same rate.
Finally, it’s tempting to overlook the role of a hypervisor’s ecosystem – that is, the availability of documentation, support, training, third-party developers and consultancies, and so on – in determining whether or not a solution is cost-effective in the long term.
To elaborate, let’s say you’re weighing up two different high-end hypervisors. One of them might offer incrementally better performance and management tools than the other, but only a fraction of its documentation and support infrastructure. In this circumstance, it’s almost always preferable to go for the hypervisor with the healthier user community.