The Waxahachie, Texas school district's IT team received a good education on virtual desktop infrastructure after implementing 900 virtual desktops.
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Robert Keith, Waxahachie's director of technology, said he quickly learned not all virtual desktop infrastructure (VDI) implementations are the same. VDI for education has a different set of requirements than other industries, he said. He also learned how important storage performance is for VDI and how much flash can help.
"Education is different from most businesses," Keith said. "We can't have one platform across several hundred desktops. Classrooms are unique, grade levels are unique, different programs are unique, and they all have different software requirements. That makes VDI more difficult."
The 8,000-student district first implemented its VDI in early 2012 across 12 buildings: seven elementary schools, three high schools and two junior high schools. Keith said the initial implementation included classrooms and labs.
Waxahachie initially used EMC VNX5300 storage arrays along with Dell Wyse zero clients and VMware View (now VMware Horizon View). Everything worked well in tests with 25 virtual desktops, but not so well when tested with 100 virtual desktops. Keith said the district spent another $400,000 to build out storage and infrastructure, but his VDI remained plagued by high latency caused by login storms.
"When you have up to 700 students going into computer labs across the district at any given time, you have login storms that can create problems," Keith said. "We found it was all directly related to the SAN [storage area network]. We have a robust network with 10 Gigabit Ethernet fiber links, Fibre Channel on the back end, brand new Cisco switching, and we were still seeing these bottlenecks. Our storage performance just wasn't keeping up with what we were trying to do."
He said the district's VNX array had approximately 1 TB of flash out of 18 TB of total capacity, "but that was before anybody knew how beneficial flash was. We were putting our images on flash and running everything else on spindle disks at EMC's recommendation.
"We finally realized our problems all came down to storage," Keith explained. "EMC wanted to sell me a completely different solution. I got tired of fighting that battle and decided to explore other options."
After researching all-flash systems, Keith picked Pure Storage FlashArray because of its performance in testing and ease of use. After switching to Pure, he said the district's VDI immediately performed better. VDI uptime went from around 80% to 99%.
Waxahachie acquired an all-flash Pure Storage FlashArray with 4.8 TB of raw capacity, but Keith said the system's deduplication allows him to exceed the usable capacity of his 18 TB VNX.
"When we put all the virtual desktops on the Pure Storage, it was running at around 18% capacity and we were getting a 17:1 data compression ratio," he said.
Unidesk helps Waxahachie manage and package apps for VDI
Flash solved Waxahachie's performance problem, but Keith said he also had a management problem.
"Managing VMware View is difficult for a technician; it takes a lot of training and experience to get comfortable with it to do things right," he said. "That's especially the case with ThinApps. Because our [school district] environment is unique, having a single image with all the software on it was not good enough because we had special circumstances creeping up on us. Our software specifications would change."
To solve the management problem, he installed Unidesk software to help manage and package applications for VDI while reducing non-persistent storage requirements. Keith said Unidesk gives him a single gold image for VDI and -- like his FlashArray -- is easy to manage.
Keith said he is also using his FlashArray for the district's 65 virtual machines and its core financial application.
He expects to expand his VDI implementation from 900 desktops to 2,400, bringing up more computer labs and expanding to office staff, which would require another FlashArray.
In addition, Keith said he can use his VDI for disaster recovery. The district rents rack space at a colocation site in Dallas and plans to set up servers and another SAN there and replicate its VMware environment using Veeam Software's Backup and Replication product.
"If we ever had a natural disaster, as long as we had an Internet connection, all I'd have to do would be to power on servers, power on my VDIs at that site, and give users access," he said. "We'd be up and running in five minutes."