When Not to Use DAS
The time to move off DAS, Asthana said, is when a business grows to need more
than four servers.
"If you have more than four servers [making up an entire data center], then DAS is not going to work for you," Asthana said. "You're then going to need an entry SAN [storage area network]."
Why is the cutoff at four servers?
"Because most DAS units cannot support more than that. The dual controller is there, and it can support up to four," Asthana said. "When you need more sophisticated storage, like for document sharing, virtualization and so on, DAS isn't going to work for you."
Dell is seeing two other trends in the DAS sector.
"Some of the software companies are making applications that work particularly well with DAS," Asthana said. "The reason they are doing it is because they want to lower the cost of the hardware. They [have an incentive] to make an overall lower-cost solution for the customer."
The other trend that Dell and HP both said they are seeing is a movement toward large clusters of DAS boxes in the Web 2.0 space that create scalable storage farms. Both vendors are competing for the expanding storage needs of social networking (MySpace, eHarmony), e-commerce (eBay, Amazon.com) and financial companies (Citigroup, Wells Fargo) that are major-league players in this space.
"New clustered DAS implementation allows for improved availability," Asthana said. "A lot of companies are looking for that. Facebook is the kind of company we are selling these clustered DAS units to."
Terri McClure, storage analyst for Enterprise Strategy Group, told eWEEK that enterprises like the ones noted above are sparking "renewed life" in the Web 2.0 space.
"What we're seeing in Google GFS, Ibrix implementations-what they're doing is layering their file systems on top of a bunch of distributed servers, making them distributed file systems," McClure said. "And they have the capability of using DAS on the back end. What they're really building is a grid computing solution leveraging DAS." These are just a bunch of loosely coupled servers with commodity-based DAS, McClure said.
What kind of data is being stored in these enterprise DAS systems?
"What's being stored is two or three copies of the data being spread across the grid infrastructure," McClure said. "An Ibrix system, for example, that does load-balancing across it can send the data to the least-busy server to deliver that copy of the file off that server. In a big environment like Google and Yahoo have-that's the type of implementation we're seeing."