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How centralised storage in a VDI environment can be made affordable

Virtualised desktop infrastructure (VDI) has now been around for a number of years. It's a potentially game-changing technology, allowing organisations to completely standardise the desktop environment, and giving IT administrators greater control over the desktop estate. However, in recent years a major barrier to the adoption of VDI has been CAPEX costs, particularly around storage.

The limits of traditional storage

One of the most important elements of any successful VDI deployment is to ensure that the user experience is as good as, or - preferably - exceeds, the physical desktop, as traditional desktop OSes expect dedicated local resources. To help achieve this, a significant amount of IOPS (input/output per second, or 'reads and writes') are required.

With traditional storage, arrays with lots of disks need to be created in order to achieve the IOPS required for the number of virtual desktops available. The main issue with this approach is scalability and cost of the solution. As the demand for more VDI sessions increases, so does the need to increase the IOPS to maintain an acceptable level of performance. This means more disks and high-end storage platforms which will very quickly become cost-prohibitive.

Solid state disks – at a cost

This brings us to our next option: solid state disks (SSDs). Although SSD storage can provide the required IOPS with fewer disks (solid state storage units), it is currently still an expensive option. Organisations may feel that a VDI initiative based on SSD storage is too expensive to be viable when compared to the cost of simply replacing the desktop estate with new hardware.

The magic of RAM

So what is the best option? Put simply – RAM.

Yes, good old fashioned memory. The last couple of years have seen companies using software solutions that utilise server RAM as storage for running virtual desktop sessions. Given that one of the biggest elements to achieving the desired user experience is IOPS, server RAM can provide this in abundance.

The software often comes in the form of a virtual appliance. This not only allows the provision of RAM as datastores on the virtualised platform, but also manages the RAM allocation on virtual host servers that dedicate the provision of virtual desktop sessions.

This solution provides two things: a good user experience at a cost-per-desktop that can be lower than a physical equivalent, and the option to easily scale your system by simply adding further host servers to the VDI pool.

Jamie McGinty is the datacentre technologies line manager at GlassHouse Technologies.