When I hear the word ‘sprawl’, I always think of stretching out by the pool on a lazy day in the sun, clutching a mojito or lying in bed late on a Saturday. That is the good kind of sprawl. However, there is an altogether more sinister use of the word. I am referring to the emerging issue of virtual machine sprawl.
In recent years, a number of new technologies have emerged in an effort to slow the growth in the number of servers and to make server provisioning, management and monitoring easier and more efficient. The most prevalent of these new technologies is Virtualization.
In simple terms, virtualization is the concept of containing many ‘servers’ within a single physical box. Imagine putting shoeboxes within a single, larger box. Anything you place in the shoebox will be inherently contained within the large box but will be separate from something located in another shoebox. This idea is effectively how virtualization works. Each ‘virtual server’ is allocated a portion of the physical machine and is separated from both the physical hardware, the operating system running on the hardware and other virtual machines by a layer called a ‘Hypervisor’. The basic concept of virtualization is shown in the image below:
Virtualization was designed with the intention of reducing cost and complexity of provisioning and maintaining servers in the datacenter. Firstly, you can have many servers running on a single piece of hardware, and since space is a valuable commodity in the datacenter and cooling is expensive, it reduces the demand on floor space and infrastructure. Secondly, since there is no need to provision hardware every time a server is needed, the process for building a new server is greatly simplified and accelerated. Also, management of these virtual machines is made easier using proprietary tools that are often provided with the virtualization solution such as VMWare’s vCenter and Microsoft’s System Center Virtual Machine Manager.
However, with any new technology comes challenges, and whilst virtualization has been hailed by some as the ‘silver bullet’ to resolve power and space concerns in the datacenter, it brings with it its own inherent problems; one of which is virtual machine sprawl.
Virtual machine sprawl refers to the result of poor provisioning and management of a virtual environment where many virtual machines are created and configured, and then are simply forgotten about. The environment sprawls out of control and the snowball effect takes over. The more virtual machines that exist, the more difficult it is to manage and find unused virtual machines. Instead of re-using machines, another is created and the cycle perpetuates. This is virtual machine sprawl.
Of course, this doesn’t happen overnight but the biggest concern is not that it is happening, but that many users of virtualization are simply not aware of it. So the next question is ‘How does it happen?’
Virtual machines are quick to provision and often at seemingly ‘no cost’ to the application owner and end user. This mindset leads to virtual machine sprawl. If we compare the process for provisioning a physical server with that of creating a new virtual machine, the situation becomes clearer. Provisioning a new physical server is often laborious and time consuming and can look similar to the following:
- Justify purchase of server
- Raise PO
- Place hardware order
- Hardware manufacturer builds/picks server
- Server shipped to datacenter
- Unpack server and rack
- Patch network and power and run cables
- Build Operating System
- Patch Operating System and install management software
- Hand over to application owner
As you can see, there are a lot of steps here and this is by no means an exhaustive list. In addition, some of these steps can take a considerable amount of time to complete, often resulting in the process taking several months. Not to mention the added complexity of finding space and power in datacenters that in some cases are nearing capacity.
Now let’s compare that to the process for building a virtual machine:
- Create Virtual Machine
- Take coffee break
- Hand over to application owner
Of course, this list is being somewhat flippant but at the same time, this idea that virtual machines can be created quickly and at little or no cost often leads to virtual machines being created for testing, application development and expanding production applications and not being repurposed or deleted when no longer used. This, in turn, leads to an increase in management overhead, increased hardware demands on the physical hosts and unnecessary licensing costs for machines that are not in use.
If virtual machine sprawl it’s not addressed, it can have catastrophic impact on cost. Boeing recently commented to Gartner that they believed that their savings through virtualization could be entirely wiped out if virtual machine sprawl is not controlled.
1E’s NightWatchman Server Edition helps to visualize virtual machine sprawl and helps companies to gain a handle on the problem, enabling them to realize the greatest benefit and ROI from their virtualization solution through efficient use of technology.