Essential guide to hybrid flash arrays
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SANTA CLARA, Calif. -- How much flash is enough? A Storage Networking World panel of solid-state storage-consuming storage administrators Tuesday discussed the merits of using all-flash arrays versus hybrid systems combining solid-state drives and spinning disk.
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Two members on the panel used all-flash arrays and two others have hybrid systems. All four said both models have benefits but their choices were influenced by their specific needs. All four moved to flash arrays to solve performance issues.
Stephan Hundley, manager of business solutions engineering for freight-car manufacturer TTX, said his 17 TB Whiptail Invicta flash array cost less than his older EMC Clariion that has mostly spinning disk with some solid-state drives (SSDs) in a hybrid flash configuration.
"I ran into performance and capacity issues and budgetary issues with my traditional [array]," Hundley said. "I implemented a lower-cost point solution [from Whiptail] with 100% eMLC [enterprise multilevel cell] flash. It was more cost-effective, very fast to implement, and we saw an incredible improvement on our database performance. That was a serious sore point for the organization."
Ron Stinson, director of IT and operations for animation studio Rainmaker Entertainment, said he needed a performance jolt for his company's massive rendering farm. It cost him less money to add an all-flash Alacritech ANX network-attached storage array than to upgrade his Hitachi Data Systems (HDS) BlueArc spinning disk NAS. He said flash helped him deal with a crush where his 500-server, 650-workstation render farm had to deliver two rendering projects 30 days apart. Rainmaker kept its HDS NAS intact, but added flash instead of upgrading the disk system.
"We were seeing load times for applications going from 20 seconds to up to two minutes," Stinson said. "We thought, 'Do we need another NAS head?' That would increase performance, but we were skeptical that we would see the results we needed."
Facing "the mother of all rendering storms" that would increase his farm to more than 1,000 servers, Stinson acquired the Alacritech flash system and noticed immediate improvement. He said his peak CPU utilization dropped from 70% to 40% after implementing flash, and network traffic off the NAS system dropped 20%. And he said it cost 40% less than adding another NAS controller.
Amit Patel, IT manager at semiconductor manufacturer Linear Technology, and Brad Taylor, director of technology operations for financial services firm Calypso Technology, said they needed more performance than they could get from spinning disk arrays, but found all-flash arrays too expensive. They both chose Nimble Storage systems that include four SSDs and 12 spinning disks, and use the SSDs for cache.
Patel said his Nimble hybrid flash gives him enough performance to run 30 virtual servers and Oracle and Microsoft SQL databases. "Nimble places the most active random reads on flash and puts sequential writes on disk, so it's faster and very reliable," he said. "Even when they're writing to disk, they're compressing it. When I heard that, I thought I would lose performance, but that wasn't the case."
Taylor said Nimble represents "the middle ground -- stellar performance due to cache and judicious use of SSDs. With flash, we're talking about magnitudes of performance increase, 10 times and in some cases, 100 times. In cases where business needs justify it, pure flash is the solution. But we have not been able to throw workloads at Nimble that it can't handle. They've taken spinning disk storage and augmented it with SSDs."
PCIe flash still too expensive?
Two panelists said they evaluated server-based PCI Express (PCIe) flash cards, but felt it was a better fit to put flash in the array. Stinson said PCIe flash could be in the cards for him, though, when it hits the right price. "We're looking at having Fusion-io PCIe cards in our workstations," he said. "It's a costly solution, but as time goes on and the price goes down, it's definitely something worthwhile. But it's not quite there yet. I can put in an SSD at one-tenth the cost and get 45% of the results I would with Fusion-io."
Hundley said he can see a role for server-based flash, but it didn't fit his needs. He said he didn't want to place PCIe cards in all of the hosts where he needed the performance gains. "We see places for it, but we needed a SAN shared storage solution, not a point solution," he said. "We're completely VMware-virtualized, and we would have had to present through all the ESX hosts."
Flash benefits for application performance
Linear Tech's Patel said the biggest benefits from using Nimble storage are a reduction in nightly backup times and an increase in reports generated from his databases. "I don't think I've even scratched the surface as far as a performance hit," he said. "I've thrown SQL at it, I've thrown Oracle at it, and we do a huge amount of reporting, and it hasn't slowed down. I have a lot of room left to grow. The application performance is so awesome, my SQL guys are always asking for more reports. Reports used to take 24 hours. Now in the morning they have reports waiting for them."
Calypso's Taylor said his biggest benefit is the ability to generate more transactions. "In our industry, trades-per-second is our key metric," he said. "We were able to see a 10 times -- and in some cases, 20 times -- improvement for transactions."
Stinson said the benefit for Rainmaker is being able to deliver more rendering projects at the same time. "Now I can take on the bigger jobs," he said. "I can increase the capacity of my farm into the thousands of servers."