IT consortium Charityshare has deployed a Violin Memory 3000 Series all-flash array to support the roll-out of up to 2,000 virtual desktops for its Age UK operations.
Violin was chosen on grounds of cost and the company's backing from HP over Whiptail and Texas Memory Systems (TMS). An all-flash array approach was chosen over mixed flash and spinning disk because of concerns that automated storage tiering features in the IBM V7000 array would not provide the availability required for virtual desktop infrastructure (VDI) operations.
Charityshare provides enterprise level IT to three charities, Age UK, The Alzheimer's Society, and The Children's Society from two datacentres, in west London and the Docklands.
Its existing storage infrastructure comprised HP EVA and Hitachi Data Systems AMS 2300 SANs but this was deemed unsuitable for use with the Age UK virtual desktop roll-out due to issues of contention for I/O suffered by the other charities on the HP SAN.
Greg Cooke, engineering manager with Charityshare said, "We had been running VDI – Windows XP on XenDesktop on VMware – for two or three years for The Alzheimer's Society, and The Children's Society from the EVA SAN. But, we had Exchange and SQL on the same SAN, and there would be issues with, for example, SQL taking all the I/O, so we decided we needed dedicated storage for VDI."
Cooke's team calculated it needed between 10 and 80 IOPS (Input/output operations per second) per user and averaged that to 35 IOPS per user, with a 5GB Microsoft Windows 7 virtual desktop. Initial deployment was to 800 users with capacity to expand to 2,000 when the other charities move to the same VDI infrastructure, which would require 70,000 IOPS.
After evaluating options including mixing flash and hard drives in a SAN and other all-flash array products, Charityshare went for a Violin Memory 3000 Series array with 12TB of MLC flash Violin Intelligent Memory Modules (VIMMs).
VIMMs are Violin's proprietary storage media, sourced via agreement with Toshiba and built onto cards with Violin software on board to provide data protection and other functions. They are hot swappable, with data failing over to spares on VIMM failure.
The 3000 Series is sold as direct-attached storage that connect to a physical server via PCIe in contrast to Violin's 6000 Series which are marketed as SAN arrays that provide shared storage via a fabric.
Other flash suppliers evaluated following recommendations from Gartner were Texas Memory Systems (now owned by IBM) and Whiptail. TMS was ruled out as too costly. Violin was chosen over Whiptail because of its backing from HP. This was seen as important by the Charityshare IT team because all-flash arrays are a new technology and the organisation wanted guarantees from a big storage supplier.
Other options examined included IBM's V7000 enterprise SAN with a flash tier.
Cooke said this was ruled out after the organisation heard of the "Monday morning problem", where the automated tiering algorithm moves data off flash to lower tier disk over the weekend because it isn't being used very much.
"Sure, it would reconfigure it to move that data back to flash but VDI needs its data from fast storage straight away," he said.
All-flash arrays have risen to prominence in the last year or two, initially from startups such as Violin, Whiptail, Pure Storage and Kaminario, and have more recently gained big supplier backing with EMC's acquisition of XtremIO and IBM's purchase of Texas Memory Systems.
