With everything moving into the cloud, virtualisation has become a very common talking point within IT circles, and has moved out into the business world more generally.
However, the cloud and virtualisation are not the same thing. Not every cloud is virtualised, and the real difference between virtualisation and non-virtualised environments runs far deeper than the cloud.
To understand virtualisation, you need to understand how storage systems, operating systems and applications interact. You need to understand the difference between hypervisors and bare metal. Keep reading to get your virtualisation crash course, and master the storage decisions you need to make to build the best environment for your IT needs — in the cloud or in the data centre.
What is virtualisation?
Virtualisation is more than just storage space. It is software that separates physical IT infrastructure like servers, physical storage, workstations etc. from computing environments and uses them to create virtual machines (VMs). Multiple iterations of these virtual assets can be run on the same hardware and make them independent of their physical infrastructure. Effectively, this is how cloud services operate, virtually subdividing cloud servers and providing access through a WAN. Why virtualisation is a far broader category, however, is that this same principle and technology can be applied to any IT environment — cloud enabled or not. Leveraging virtualisation enables businesses to increase their operational efficiency, flexibility and utility while actually reducing IT costs. You’re able to maximise the use of resources by reducing the tendency to waste server capacity when individual servers have to be dedicated to specific applications and tasks. In virtualised environments, everything can be subdivided and partitioned so that every element of your IT stack is fully used, while different applications and data retain their independence and are allotted set amounts of resources in what are, effectively, discrete environments.What are hypervisors and why are they important?
In order to properly understand virtualisation, one needs to understand the role of hypervisors. Hypervisors are the software solutions which manage virtual machines. They are effectively the operating systems for virtual machines, controlling all of their constituent parts. A hypervisor enables users to overcome the inherent limitations of their physical IT infrastructures. They allow users to host several different virtual machines on a single piece of hardware. Each virtual machine is capable of running its own programs in the exact same way in which they would usually operate. Except that instead of relying on the hardware’s physical processor, memory and resources, the hypervisor is actually allocating virtualised resources to run the programs. Their growing presence in the world of business may lead one to believe that hypervisors are a recent phenomenon but the first hypervisors were actually utilised in the 1960s to allow different operating systems to work on a single mainframe computer. Around the mid-2000s, Linux and Unix systems started making use of virtualisation technology to expand hardware capabilities and improve reliability, and this led to widespread adoption once the scope of their application became clear.Pros of virtualisation
Being able to transcend the capabilities of your hardware is an appealing prospect for operations with growth in mind. Indeed, virtualisation has many potential pros:- Cost effective — Virtualising your hardware allows you to maximise its use. It also keeps costs predictable by avoiding unnecessary scaling.
- Flexibility — Virtualised environments allow you to more flexibly engage with your IT infrastructure, maximising its use, but also experimenting with new applications without having to go out and invest in new hardware. Fundamentally, virtualisation allows for a more flexible approach to IT in general.
- Uptime — The ability to flexibly bounce applications throughout your hardware stack, creating hardware agnostic IT processes, helps reduce the risk of downtime. If something goes wrong with one server, you can simply move those virtual machines to another part of your network without causing issues or suffering delays.
- Fast deployment — Because there’s no need to set up physical machines, create local networks, or install other IT components when changing your VM configuration, virtualisation allows for quick and easy deployments.
- Energy savings — IT costs aren’t the only overheads which can be reduced by virtualisation. Virtual machines are much cheaper to run because they don’t have the same cooling or operational costs of a data centre.
Cons of virtualisation
It’s easy to see why virtualisation may be beneficial for a wide range of businesses and operations. But does it have any disadvantages?-
- Compatibility limitations — Not every application or server is going to work in a virtualised environment. You need to understand your application compatibility before jumping into virtualisation.
- Performance impact — Hypervisors are another software layer that sits between your applications and servers. In a sense, you are running two operating systems rather than just one. Although the performance impact of a properly configured hypervisor is limited, it still exists. In like for like testing, virtualised environments will always underperform bare metal ones.
- Upfront costs — Although VMs and virtualisation can reduce costs in the long run, the transition from a legacy environment can be costly.
- Scalability issues (maybe) — Because there are multiple entities sharing the same resources, growth can create lag within virtualised networks. On the other hand, hardware agnostic applications can make it easier to scale — so this one depends on your specifics and how you build your network.
What is bare metal?
A bare metal is a single-tenant physical server which is stored on your business premises. It is a physical computer that’s designed with the specific needs of your operation in mind. It can run dedicated services without any interruptions or lapses in service for extended periods of time. Bare metal servers are highly stable, durable, reliable and customisable, allowing operations to attune them to their unique needs. Their dedicated nature mitigates many of the risks and deficiencies associated with virtual machines and networks. Resources are readily available, tenants have root access and performance is more consistent because network latency is minimised.Pros of bare metal
It’s easy to see the potential benefits of investing in a bare metal server:- Speed — With bare metal hardware, your applications run straight on the servers. With the hypervisor out of the way, every last bit of your server’s computer potential can be directed towards applications.
- Security — Stripping back hardware to its minimum components, and removing software overlays, you remove points of attack. Although hypervisors can be very secure, nothing beats the security of bare metal.
Cons of bare metal
Yet, while bare metal servers have their advantages, they are not viable for every operation. They have some inherent disadvantages including:- Cost — Because bare metal servers can go under utilised, you over all IT costs can be higher when using this stripped back approach.
- Agility — Because they use physical resources they are less agile and harder to scale horizontally than virtualised solutions.
