Virtual desktop infrastructure (VDI) is a game-changing technology that allows organisations to provide complete standardisation to the desktop environment as well as giving IT greater control over the desktop estate.
However, a major drawback to the adoption of VDI is the capex costs. This is particularly the case for VDI storage, which is one of the most important elements to any successful deployment because you want to ensure the user experience is as good as, or preferably better than a physical desktop with its dedicated local resources, and to avoid the dreaded boot storm.
Good VDI storage needs adequate IOPS. This can be achieved with lots of spinning disk, but the difficulty with this approach is scalability and cost of the solution. As 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 start to become cost prohibitive.
This brings us to the next option which is flash solid state disk (SSD). Although flash storage can provide the required IOPS with fewer disks, it is currently still an expensive option. A VDI initiative based on flash can seem too expensive to be viable compared to the cost of replacing the desktop estate with new hardware.
So what is the best option? Put simply – RAM. Yes, good old fashioned memory. And, the last couple of years have seen suppliers develop caching software solutions that use server RAM as storage to run virtual desktop sessions.
The biggest requirement to achieving the desired VDI user experience is IOPS, and server RAM can provide this in abundance. The software often comes in the form of a virtual appliance that provisions RAM as a datastore on the virtualised platform but also manages RAM allocation on virtual host servers.
Such a solution can provide the user experience at a cost per desktop that can be lower than a physical equivalent and is very easy to scale by adding further host servers to the VDI pool.
Jamie McGinty is datacentre technologies line of business manager at GlassHouse Technologies (UK).
This was first published in September 2013