These file systems, examples of which include ADIC's CentraVision, SGI's CXFS, Tivoli's SANergy, and soon, it would seem, IBM's Storage Tank, work by taking the file system off the host, and running it directly in the network. As such, SAN file systems deliver "a single point of management and a single namespace," and "common management for all files on the network," IBM writes in a white paper.
More to the point, SAN file systems provide concurrent, heterogeneous file sharing, "where the reader and writer of the exact same data can run different operating systems," IBM writes.
Certainly, that's what end users usually turn to SAN file systems for. For example, ADIC customer Digital FilmWorks, a digital effects studio, uses CentraVision to allow multiple users to make simultaneous changes to movie frames. "A single frame - up to 100MB - might need to be used four times, by four different people," says Peter W. Moyer, Digital FilmWorks' president. "And all of them need access to that image."
When it comes to Storage Tank, think "SANergy on steroids," says John Webster, senior analyst at the Data Mobility Group in Londonderry, NH. With it, information (metadata) about
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files is stored away from individual servers, and in the network instead, while data transfers happen directly between the client and the storage device.
"It's a classic example of separating the data path from the control path," says Nick Allen, vice president and research director for storage at Gartner, a tack he says EMC takes with its HighRoad software.
"The gotcha," Allen adds, is that with Storage Tank "you need software on every client, and a lot of people don't want to do that."
According to IBM, Storage Tank will be available sometime in 2003, and will run on a cluster of dedicated Linux servers, with initial client support for AIX, HP-UX, Linux, Solaris and Windows 2000/XP.
ADIC, meanwhile, has made CentraVision a central component of its new StorNext suite. In it, CentraVision and ADIC Intelligent Storage Manager work toward better storage resource utilization by migrating data to different types of media according to individual files' usage characteristics.
Historically, though, the appeal of a SAN file system lies in concurrent heterogeneous file sharing. But whether that's desirable outside of certain niche markets is still up in the air. "It's the holy grail," says Arun Taneja, senior analyst at the Enterprise Storage Group. Meanwhile, Gartner's Allen is a bit more reserved: "It's not so much that we want simultaneous access to data, it's that we want to create the data once and have it in one place."
That's especially true when it comes to large files, like those found in the creative and technical computing space, says Bob Murphy, marketing manager for SGI's complex data management group. But in general, "files are getting so much bigger," Murphy says. To that end, "SGI is working with other parties to deploy CXFS out to a broader use," he says, and will announce partnerships this summer.
This was first published in June 2002