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The Case for Low-Latency File Virtualization

February 4, 2008 - Penny Crosman

The best idea in large-scale storage in the past decade has been storage virtualization software, also called storage fabric -- hardware-agnostic middleware that lets IT managers intelligently manage the storage of files and data. In an ideal implementation, storage virtualization saves network, server and storage managers from having to re-provision files and data to new devices when servers and storage devices become full, and reduces disruption and downtime for users who need to access information. Yet the harsh reality is, many storage virtualization solutions that claim to be hardware agnostic are really tied to specific storage products. New to the table as of today is a network switching appliance that aims to virtualize file storage to any type of storage unit, from F5 Networks.

Why buy another piece of specialized hardware, when part of the problem is the complexity of having so many hardware storage devices? "The reason is, we don't want to impact performance or latency for file operations," says Nigel Burmeister, director of product marketing for F5's Acopia data solutions division. An added layer of middleware software will add latency and impact performance, whereas a hardware can handle file management tasks "at wire speed and at high scale and capacity," he says.

With the Acopia FreedomFabric appliance, files continue to be stored in file servers, network-attached storage devices or storage area networks. The appliance provides virtual-to-physical mapping of files so that users and applications don't access physical storage directly, they access it through a virtual namespace. Then firms can perform information lifecycle management to files, applying policies such as 'store iTunes files and archived reports on less expensive storage devices,' and 'store high priority files in tier one storage.'

How does this intervening appliance not slow down access times for these files? "It's just adding another network hop in the path," Burmeister says. "The latency running through a switching platform is orders of magnitude lower than running through a layer of software middleware. It's unnoticeable."

The other benefit of hardware-based file virtualization, Burmeister says, is scalability. " A piece of software cannot process the same number of transactions per second at a latency that a hardware-based appliance can," he says. For instance, one Acopia switch can scale to a couple of billion files, he says. Software solutions on general purpose PCs can only handle 40-50 million files.