HP Straddles The Virtualization Line

Mark Sorenson, vice president of HP's storage software, was discussing the company's new Continuous Access Storage Appliance (CASA) product when he dropped an interesting observation: "What we discovered was that [the industry] had done a lot of talking about virtualization as a technology, but not enough discussion of it as a solution."

The statement was lacking enough marketing propaganda that even a Sun Microsystems executive gave it a nod. "I absolutely agree with him," says Bud Broomhead, director of new business ventures for network storage at Sun.

HP storage experts came to that realization as they met to decide the fate of certain Compaq and HP products after the merger,when HP suddenly became the owner of not one, but two storage-virtualization products. Here's some history: Compaq storage engineers had been working on perfecting their virtualization software, called VersaStor, for more than a year before the HP-Compaq merger was completed. It had not gone to market as an actual product when HP announced the $350 million acquisition of StorageApps in July 2001.

Both VersaStor and the StorageApps product do virtualization,meaning the software logically pools the physical disk

drives in a system so users have more control in allocating capacity. But each does the process of virtualization differently: VersaStor is an out-of-band technology, while HP's acquired product, StorageApps, is in-band.

"Our engineers analyzed both technologies and found they had complementary strengths," Sorenson says. "If you think of a metaphor, it's as if both companies were painting a wall. HP started from the right. Compaq started from the left."

Some say virtualization works best when it's in the data path, placed between the physical storage devices and host systems. Others say the out-of-band method is best because it does not add to latency problems. HP had decided to blend the technologies over time. And that statement became more of a reality on Jan. 21, when HP and Brocade announced a partnership to deliver a virtualization and replication solution.

Come this summer, HP will release into beta its CASA solution, which blends StorageApps' replication software along with VersaStor's out-of-band virtualization. That appliance will work in tandem with the Brocade Silkworm Fabric Application switch that maps tables and uses its intelligence to direct data traffic,specifically routing data slated for replication to the CASA appliance. "So it's a hybrid approach, where the vast majority of data is processed out of band. But for replicated data, it's an in-band solution," Sorenson says.

StorageApps' in-band product has solid replication and snapshot capabilities. On the other hand, VersaStor offers a more elegant approach because it does virtualization at the block level. The problem was that engineers were still trying to perfect VersaStor's replication capability,a job that Sorenson conceded was going to take more time and money. "The replication part was not there yet," he says.

So, does this mean HP believes management intelligence should reside solely in the switch?

"I wouldn't use the word solely," Sorenson says. "We don't believe that one solution fits all. We will continue to do technologies where it makes the most sense."