Late last year, Washington Trust Bank was deploying a virtual desktop infrastructure (VDI) out to the bank's home loan officers and wealth management group, as part of the bank's overall migration to Windows 7, when something went terribly wrong.
Washington Trust wanted to take advantage of the user mobility and reductions in hardware promised by desktop virtualization, in which operating systems and user applications are run on servers in the data center instead of hosted separately on each employee's PC. In a virtual desktop environment, PC towers are replaced by small boxes to which keyboard, mouse and monitor can be connected.
Two types of virtual boxes from Wyse, now owned by Dell, were under deployment at Washington: zero clients, which have no operating systems at all - just outlets to plug in essential peripherals; and thin clients, which have ROM-based Windows 7 operating systems embedded into them, but contain no disks.
To access their applications, the Spokane, Wash.-based bank's employees would need only log in onscreen via an interface called VMware View, which users can launch from their workstations, laptops or iPads.
Testing in which the bank's Dell R7N servers and EMC CX4 storage area network showed no issues had IT staff confident the bank had the infrastructure to support virtualization for about 500 users. But as IT virtualized the bank's 90th user, the system's performance plummeted. Complaints spiked about minutes-long loading times for oft-used applications like Microsoft Outlook. Christopher Green, Washington Trust Bank's vice president of IT infrastructure systems, and his colleagues checked the processor and memory use in the server host of the VDI systems. They looked at the network for bottlenecks in the routers or switches.
They spotted the problem in the last place they looked: the storage area network. The storage processors on the SAN "pegged out at 100 percent during these times of reported slowness," Green says. "Yet we thought we had plenty of horsepower."
Adding more storage processors or solid-state disks was a non-starter. That would mean another $100,000 in hardware costs. It was while researching the problem on the Web, Green found something interesting - Windows 7 required almost twice the input/output operations per second (IOPS) that Windows XP did. He then came across a discussion thread on a forum where one post mentioned Atlantis Computing was marketing performance optimization software called ILIO that, according to the Mountain View, Calif.-based vendor, could reverse the slowdowns caused by input/output storms exacerbated by Windows 7.
Meanwhile, Jim Brockett, Washington Trust Bank's CIO, demanded a decision be made by mid-January on whether to continue the migration to Windows 7, given the performance problems.
Green says initial testing from a downloaded trial version of ILIO showing "phenomenal" reductions of the input/output streams to the storage area network convinced him that the bank should adopt the software. The positive reactions from many of the 90 users already on the VDI who were deployed on ILIO shortly thereafter supported his convictions about the software. After deploying ILIO, IOPS were reduced on the bank's SAN to 350 from about 3,500 IOPS recorded previously. That's because all reads and writes to or from the storage array are cached on the local ILIO device, so users tap common information on applications from the local host, versus going back to storage to pull the data. ILIO also repackages the way Windows reads and writes, so that instead of reading or writing in random 4k blocks as is typical, ILIO combines them into 16k blocks, turning what would have been four reads or four writes from the storage array into one.
ILIO also performs data de-duplication so only what needs to be is written or stored. Because of that, instead of needing 188 disks on the SAN as initial calculations estimated, the bank needs only 15 storage disks to support 500 VDI users.
The bank hosts about 50 Windows 7 virtual machines on seven servers. ILIO sits on each of the host servers as just another virtual machine, but remains between the virtual machines and storage. The ILIO presents itself to the other virtual machines as an NFS file share. The virtual machines are pointed at the ILIO instead of at the physical storage array, so all the reading and writing goes to the virtual software appliance, which determines what goes to or is pulled from storage.
"It allowed us to pick up our Windows 7 migration on the VDI platform again in mid-January," Green says. "Now we're at about 350 to 375 users." He expects the bank will finish migrating to Windows 7 by September.
CASEFILE
BANK: Washington Trust
PROBLEM: Traditional storage methods sap thin-client performance during operating system migration.
SOLUTION: Deploy software to streamline storage processes.
