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Growth in teleradiology studies spurs SAN upgrade

John Moore | Oct. 29, 2013
As a virtual radiology firm saw its workload nearly triple, storage performance suffered. That, in turn, impacted the underlying database, to the point that maintenance jobs overlapped. Rather than rewrite the database, Virtual Radiologic opted to upgrade it SAN -- and saw latency drop dramatically.

A fast-growing teleradiology firm found that a slowing storage-area network (SAN) interfered with its business of getting medical images out to radiologists for interpretation.

Virtual Radiologic offers radiology services to hospitals and radiological practices nationwide. The company provides gap coverage for evenings and weekends - in some cases, it actually provides a healthcare organizations entire radiology department.

The company, also referred to as vRad, builds virtual private network (VPN) tunnels over the Internet to its healthcare customers. Customers send their images - X-rays, magnetic resonance imaging (MRI) scans and the like - to vRAd's Minneapolis data center. The data center then pushes the images to vRad's 450 radiologists, who read the scans and dictate reports that go back to the customers. The company has more than 3,000 radiology group and hospital customers.

A SQL Server database application essentially matches each incoming image to the doctor best suited to review it. The application must quickly crunch a number of variables in real time to determine where the images should go. The company's SAN, however, began to slow as vRad's radiological workload expanded. Read/write times lengthened to 30 milliseconds, according to Patrick Williamson, IT manager at vRad.

"As time went on, and our database grew and our volume grew, the SAN just couldn't hold up," Williamson said. "We were outgrowing the Compellent SAN."

Against that backdrop, vRad deployed a new SAN, built on hybrid disk-flash storage arrays from Nimble Storage. The iSCSI SAN operates within a heavily virtualized environment, with all development servers and a growing portion of production servers having been converted to virtual machines in a VMware environment.

The new SAN, which went into production earlier this year, addresses the company's performance issues- latency is now less than a millisecond with Nimble - and boosts storage capacity. It also contributes to a reduction in data center floor space requirements and the resulting cost savings.

Outgrowing SAN 'Classic Story' of Latency, High Database Demand
Matthew Ushijima, principal consultant at GlassHouse Technologies, an IT infrastructure consulting based in Southborough, Mass., has seen vRad's situation emerge a number of times in his experience as an IT manager and consultant. As a business grows, demands on key applications increase, he says, and the database load becomes higher than the initial specification. Organizations employing a mid-tier array in such a setting may lack sufficient head room to expand.

"It is a classic story in IT," Ushijima said.

In vRad's case, its Compellent SAN worked well initially, when the company was conducting 9,000 studies a day. "We got the performance out of it that we needed," Williamson says.

As the volume edged upwards toward vRad's current peak of 24,000 studies per day, storage performance suffered. "Latency was a huge issue," he says. (Latency is a measure of the time it takes storage to respond to an I/O request - to read or write data - from an application.)


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