By Heidi Biggar
Since its acquisition of Compaq, Hewlett-Packard has been in the difficult position of trying to juxtapose a two-platform storage virtualization strategy—one based on the former Compaq VersaStor platform and the other based on the StorageApps virtualization appliance (now known as CASA). HP acquired StorageApps for $350 million in the fall of 2001, making it one of the storage industry's most costly buyouts.
"We can't see how they can keep both platforms," says Diane McAdam, a senior analyst at the Data Mobility Group consulting firm. "Our bet is that VersaStor wins out, and CASA loses."
Despite broad skepticism, HP officials remain adamant that the company will keep both technologies and that it will roll out the first "blended" virtualization environment in the fourth quarter.
"CASA and VersaStor are complementary, not redundant," says Don Langeberg of HP's network storage solutions (NSS) group. "CASA provides heterogeneous disk/host support, while VersaStor provides scalability and performance." Langeberg claims the two virtualization architectures will give end users the best of both worlds: heterogeneity, scalability, and performance.
The idea is to embed VersaStor technology in an intelligent switch (e.g., a Brocade Fabric Aware Platform switch) and in the Continuous Access Storage Appliance (CASA), according to Langeberg. The VersaStor code, which serves as the communication protocol, then directs storage traffic based on the storage services (e.g., replication, volume management, and data management) that are applied (see diagram).
The switch decides if the I/O goes direct to the storage device or if it needs to be replicated first. If no services are to be applied, then the I/O goes direct to the storage box at wire speeds. However, if the I/O needs to be replicated, then the switch directs it to go through the CASA box first, explains Langeberg.
At its ENSA@Work conference earlier this year, HP announced a joint development agreement with Brocade to embed VersaStor code into Brocade's new SilkWorm Fabric Application Platform. Brocade acquired the platform in its purchase of Rhapsody Networks (see "Brocade to acquire Rhapsody," InfoStor, December 2002, p. 8).
Beta testing of HP's integrated virtualization environment is scheduled for the third quarter, with production shipments expected by year-end.