Kingston University has deployed Atlantis Ilio flash caching software to provide remote users with virtual desktops and has achieved throughput of up to 600 input/output operations per second (IOPS) for 1,000 users.
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The university is distributed across four main campuses with multiple remote sites. It has 25,000 users, including 2,500 staff.
Its IT infrastructure was spread across these sites in a piecemeal way, with storage arrays from IBM, EMC, Sun and other suppliers, as well as many instances of direct-attached storage (DAS) on servers.
As the university moved towards a virtualised environment, the existing IT and storage infrastructure soon showed its inadequacies, said technical architect Daniel Bolton.
“We had several VMware environments,” he said, “and just keeping the storage going to support them was a challenge, with regular disk failures occurring. Some of the storage was 10 years old.”
In 2013, the university underwent a total IT refresh, including standardising on IBM V7000 storage with IBM’s Storage Volume Controller (SVC) storage-virtualisation hardware. It has around 1PB of capacity in total, split between mostly serial-attached SCSI (SAS) hard disk drives and about 60TB of flash.
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As a sub-project, Bolton’s team wanted to provide virtual desktops to users working from home, although the university retained physical desktops for most use cases. This involved providing around 1,000 non-persistent virtual desktops via VMware view.
Trying to size virtual desktop infrastructure (VDI) IOPS requirements was tricky, said Bolton.
“Because users log on from home there are no boot storms to deal with,” he said. “But we do have a very large range of IOPS requirements. Some apps, like Adobe Photoshop, are very disk-heavy. We calculated we needed IOPS ranging from 20 to 25, right up to around 500 or 600.”
To provide smooth access over such a range of requirements, Bolton turned to Atlantis, a flash caching software provider to carry out a proof of concept.
The Atlantis Ilio flash caching product deals with the massive and random input/output (I/O) demands placed on storage by virtual desktop environments.
Physical desktop devices have access to direct-attached storage (DAS) on boot-up and subsequently. However, virtual desktop user configurations and data are served remotely, so I/O from users comes in randomly to the server and can be demanding in terms of volume of throughput.
The Atlantis flash caching product stores virtual desktop images in a server cache to ensure rapid access.
“Atlantis has kept the cost down and is easy to use,” said Bolton. “But in terms of performance we can run all the virtual desktops flat out and still get 500 IOPS each, which is better than with physical desktops. We get latency of about 0.8 milliseconds via SVC and 0.3 or 0.4 milliseconds via Atlantis.”
Bolton said Kingston University also plans to use the Atlantis USX storage-virtualisation software at some point. USX allows IT departments to create array-like pools of storage from heterogeneous media and includes data deduplication to reduce the amount of actual capacity occupied.
“We don’t need USX now because we have new storage hardware in place, but when we need to grow capacity we’ll deploy it. We expect to save between 50% and 60% in capacity, or be able to use cloud storage, which USX also allows,” said Bolton.