VDI issues: How to use SSD to improve performance
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Price is considered a hurdle to deploying solid-state storage, but some organizations find flash systems can actually save money for specific applications.
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That is especially the case for newer storage systems designed to take advantage of solid state at lower costs. Colby-Sawyer College in New London, N.H., spent an estimated one-third as much with a NexGen hybrid SSD array for virtual desktop infrastructure (VDI) as it would have with traditional disk storage. And Fort Worth, Texas-based Aerospace Optics Inc. acquired a Nimbus Data S-Class all-SSD array for about 10% of what it would have cost to buy hybrid arrays from later vendors.
Hybrid flash for VDI storage
David Blaisdell, assistant IT director at Colby-Sawyer College, said he expects his NexGen n5 storage system to allow him to implement VDI storage for $28 per desktop. That figure is speculative because it is based on supporting 600 virtual desktops with one storage system. The college has less than one-third of that number of virtual desktops now, but Blaisdell said his testing indicates the SSD-powered NexGen has the horsepower to support all 600.
The first phase of Colby-Sawyer's desktop virtualization project includes 200 desktops. The college acquired 300 VMware View licenses, and Blaisdell said he has server hardware to accommodate 300 virtual desktops to get halfway to his eventual goal.
"We have plenty of performance for the 300, and I think one storage unit will give us all the capacity and performance for our target of 600 to 700 virtual desktops," Blaisdell said. "We're seeing a peak of 4,000 IOPS now when generating new desktops. But in testing with Iometer and Windows 7, we can push 25,000 IOPS with one virtual desktop. If we can get to 600 virtual desktops with one storage system, I'll be quite pleased. And so far with our numbers, it looks like we'll be able to do that."
Blaisdell said storage performance was his major obstacle for VDI storage: "We didn't need a big storage footprint in terms of terabytes, but we did anticipate a need for performance."
Colby-Sawyer's main storage is a Hewlett-Packard Inc. (HP) LeftHand SAN. Blaisdell said he considered adding more HP storage to get through the first VDI phase, but "we would have to come back 12 months later and add storage as we expanded. So, that's when we started looking at these other next-generation storage vendors that could provide higher performance."
Blaisdell realized flash would be required. NexGen uses Fusion-io Inc. ioDrive solid-state devices along with spinning disk in a hybrid configuration. He knew members of NexGen's team from their days with LeftHand, so he brought in an n5-100 system with 1.28 TB of solid-state storage and 22 TB of raw hard-drive capacity for testing. He purchased it about a month later, in May.
"If we had used traditional spinning disk and bought enough up front for 600 desktops, we would've spent three times what our budget was," Blaisdell said. "We would've probably purchased enough for 200 desktops for phase one, and then would have had to add more for performance."
The NexGen box remains dedicated to VDI, although Blaisdell said he may add another system for disaster recovery after the vendor delivers asynchronous replication. He will likely eventually use NexGen for SQL Server and other applications with high performance requirements, he said.
All-SSD array accelerates SQL database
Michael Perry, vice president of information systems for Aerospace Optics, said he found Nimbus was a lower-cost option to mainstream storage vendors. Before looking at Nimbus, he said he was considering buying a hybrid EMC Corp. VNX with less than one-half terabyte of solid-state drives for more than 10 times what his Nimbus S-Class all-SSD array cost. Another alternative was to add flash to an underperforming NetApp Inc. FAS2020 array, but that would have cost $100,000 just for an additional 2 TB of flash.
"We're a small company. I just could not see going [to] the president again saying, 'You know that $40,000 I just spent? Well, I didn't get my money's worth. So now I want to spend another $100,000,'" Perry said. "EMC was in the range of $64,000 just to get less than half a terabyte raw. The Nimbus system cost $37,500 for 2.5 TB. You can buy 10 Nimbus systems for the price of an EMC box."
Perry said he began researching all-SSD arrays last November as part of a project to virtualize as many of Aerospace's servers as possible. He settled on Nimbus after talking to the vendor's executives at a trade show in April and doing more research afterwards. "My consultant got on the line with their CEO after the show and discussed their architecture. Our question was, 'Was it a true SAN from the bottom up, or PC-based with a bunch of drives in it?'"
Satisfied the S-Class is a true SAN, Perry installed a Nimbus system as storage for Aerospace Optics' frequently accessed enterprise resource planning (ERP) application, which uses a larger SQL Server database. He said the flash array reduced his SQL backup times from 18 minutes to three minutes.
Perry said he and his users are now hooked on flash. He uses his NetApp FAS2020 disk systems for backup, placing one at a colocation site and using SnapMirror to move server images off-site.
"I'm the kid on the motorcycle who's discovered he likes going 150 miles per hour, and he just can't go back to 55," Perry said. "Once you've had the speed and responsiveness of an SSD, you just don't want to go back. My people need their stuff up, and they need it to be responsive."
Perry has 24 production employees who hit his ERP server for training reports, videos and other high-resolution content, he said. "If the system wasn't responsive, you have 24 people waiting five seconds every minute. Before long, that adds up to $100,000 of lost productivity in a year."
Perry will likely add a second S-Class system soon, he said. "There's a saying in IT that you can never have too much bandwidth, too big of a display or too much storage. You can eat up storage fast."