DigiTar Uses Hybrid SSD-Hard Drive Storage to Boost Performance

The cost per IOPS dropped from $6 to $1 by adding an SSD front end to a Sun storage system, the company's CTO says

November 22, 2008

4 Min Read
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Email security service provider DigiTar, based in Boise, Idaho, has been providing services and support to companies in the financial, legal, government, and other vertical industries since 2004. Its clients range in size from five employees to 50,000, so there isn't a single service or solution that fits them all. But the one thing they all want is consistently reliable, insightful, and responsive service.

"We are in a highly competitive industry with competitive margins," says Jason Williams, DigiTar's chief operating and technology officer. "As we approached our storage needs, we wanted to reduce operational costs -- such as the cost of storage itself and the time it was taking for us to manage storage."

What DigiTar wanted was the flexibility of more efficient and cost-effective storage that would facilitate better service to clients. "Part of what we wanted to deliver to our client base was more flexible analytics and reports that presented clients with fresh information that they had never seen before," Williams says. "Additionally, many of our clients wanted to use us as an archiving facility for their reporting and results."

To answer the challenge, DigiTar embarked on an evolutionary storage journey that began with low-end storage arrays employing 7,200 RPM SATA hard drives and moved to clustered pairs of Sunfire X4500 storage servers from Sun Microsystems. "Before making the move to the X4500, we had looked at several other storage options in the market," he says, "but again and again, Sun's solutions and scalability were best suited to our needs."

DigiTar then made another move to boost performance -- adding solid-state drives. It conducted extensive internal performance benchmarks to substantiate the benefits of a blended SSD-hard drive system. DigiTar's original deployment of Sunfire X4500 servers used 48 spindles or hard drives that each delivered 75 IOPS per drive for a total of 3,600 IOPS per server. DigiTar then moved to a "mixed" disk configuration that put in a single solid-state drive (SSD) as the front end to the hard drives. In performance tests of the new "hybrid" of SSD and hard-drive storage, the total IOPS zoomed to 20,000 -- more than a fivefold increase."We found that, suddenly, our cost per IOPS on the X4500 had dropped from $6 per IOPS [without an SSD front end] to just $1 per IOPS [with an SSD front end]," Williams says. "This gain was substantial. But it became even more remarkable when we compared it to our data for the old storage arrays we had formerly used. In that environment, our cost per IOPS was around $43."

The DigiTar migration to SSD/hard-drive hybrid storage was transparent to customers, but the end results were just as striking as the price-performance, he says. Clients now are getting faster turnaround on reports and analyses, and they now have more views of their data and can get a better understanding of their email operations.

Just as importantly for DigiTar is the amount of flexibility the SSD-inspired storage is giving its internal database administrators, who focus on supporting the customer base. "DBAs all have their own database servers, and can now change the storage underlying those databases without fear of impact to others," Williams says.

Williams notes the company now has a highly scalable, cost-effective storage system that positions it well to grow and expand its business. DigiTar originally began as a Linux shop, and then moved to OpenSource Solaris, which gave it better reliability and performance. The company continues to review all system components, including storage, in an effort to improve its operations and its responsiveness to clients.

"Our storage direction will continue to be evolutionary. The goal is not to wholesale replace hard drives with SSDs. Rather, it is to front-end hard drives on servers with SSDs for much improved performance, simplified management, and lower costs. In other words, we are simply changing our provisioning, not our architecture."The effort includes experimentation with Sun Sunfire 4240s, which Williams believes will save DigiTar an additional $30,000 per data cluster. That would be in addition to the $100,000 per data cluster that he says the X4500 already saves. DigiTar is considering migrating some of its data load to Sunfire X4240 servers, each of which has a 16-drive chassis that DigiTar provisions as 13 hard drives, an additional two hard drives reserved for disk mirroring and backup, and a single, front-end SSD that boosts performance for the entire configuration.

"This is about delivering service excellence to our customers and continuing to reduce our operational costs -- like storage -- in the face of a highly competitive business environment," Williams says. "We will continue to exploit new technology provisioning approaches that combine SSD with hard drives to deliver the finest analytical products to our customers."

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