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The university has 23,000 students and 2,500 staff and has 5,000 client devices running around 4,000 apps that are supported from two datacentres.
Wolverhampton’s first forays into VDI started two years ago when desktops were virtualised at the institution’s performing arts hub, and later the student virtual learning centre and student residences, all using the Dell vWorkspace virtual desktop software and Microsoft Hyper-V.
“The market leaders were cost prohibitive,” said Dean Harris, assistant director of infrastructure at the university. “Hyper-V was more attractive in cost terms because of the deals Microsoft has with the public sector.”
All existing VDI used direct-attached disk on servers, but Harris said his department started looking at flash storage to speed VDI I/O for a new staff system comprising 150 desktops which will go live in December. Student virtual desktops are non-persistent – ie, no desktop settings are saved – but staff desktops are persistent and run from a separate disk image.
“VDI had been on local storage, which is fine for non-persistent desktops, but for persistent images we needed shared storage,” said Harris.
The university already has a pair of HP EVA 8100 SANs, but these are coming to end of life. Also, the SAN storage fabric is built to provide set service levels from the central datacentre using high-availability failover. Integrating VDI to fit in with the existing structure would have incurred higher than necessary costs, said Harris.
More on flash-based storage
Harris’s team evaluated a number of all-flash array providers, including Fusion-io and Violin Memory, but eventually settled on a Nimble Storage CS220G-X2 with 16TB total capacity made up of 640GB of flash cache and the remainder on low-cost, low performance Sata drives.
Hybrid flash storage uses tiering software to shift hot data to flash storage while retaining low-cost Sata for bulk storage with data deduplication to optimise capacity usage. Hybrid flash is one among a number of approaches – alongside all-flash arrays and PCIe flash – bringing the low latency and fast access of flash to the datacentre.
Harris said Nimble was simply the most responsive of the flash suppliers the university saw when procuring the solution, and also won in terms of cost.
“Nimble walked into a room full of skeptics. But we liked the idea of hybrid flash storage with high levels of redundancy and availability built-in. Also, the cost of pure flash storage was horrendous,” he said.
Key benefits, said Harris, are the sheer performance available to the VDI project and the ease of management of the Nimble array.
“We’ve seen a significant increase in IOPS compared to our existing VDI deployments, with 70% or more better performance,” said Harris. “It makes a huge difference in the VDI environment, with login and logout times and the user experience hugely improved," he said.
“You need a very specific skillset and experience to manage the [HP] EVAs. But Nimble has a web interface and is easy. We used no professional services in the deployment.”
Currently the university only has one Nimble box installed, but a second is planned to provide redundancy. “Now we are wiser about the potential capabilities of Nimble, we will get a second one in to cluster with the first,” said Harris.
The deployment took place in conjunction with Nimble partner, Manchester-based R-Com.