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IBM Pushes Shark's Copy Buttons: Page 2 of 4

"I think the vendors' claims about bandwidth are arguable... but there's not enough candy in the bandwidth question to convince customers to switch vendors," he says.

Tuckwell, for his part, says theoretical maximum performance claims are meaningless when it comes to real-world customer environments. "It's like arguing whether a Maserati, Lamborghini, or Ferrari can go faster on a public highway," he says. "If you go faster than 70 mph, you go to jail."

With its latest tweaks to the Shark, IBM says it has focused on boosting the system's business-continuity capabilities. For example, version 2 of FlashCopy, the Shark's point-in-time copy utility, is able to perform setup 10 times faster than before. Previously, FlashCopy setup could take up to 8 seconds for very large volumes, during which time the data is unavailable; with version 2, that setup is less than 1 second.

Other features of FlashCopy V2: It can copy to up to 12 targets, compared with only one previously; it's able to span multiple logical storage systems; and it provides dataset-level copy for S/390 and zSeries systems.

PPRC V2, meanwhile, includes an Asynchronous Cascading feature that combines synchronous and asynchronous replication without requiring any additional software. For example, a user can perform a synchronous copy across a metro-area network to a second facility, and then have that immediately cascade to a third site asynchronously. To achieve the same functionality, an EMC customer, by comparison, would need to purchase both Symmetrix Remote Data Facility (SRDF) and TimeFinder.