"VSANs allow different fabrics to exist on the same switch, and each is unaware of the existence of other fabrics," says Moore.

Vendors are exporting this technology with switches that extend their traditional Fibre Channel-only range to other protocols, such as Fibre Channel over IP, Internet SCSI and Fiber Connectivity.

Cisco Systems Inc.'s MDS Multilayer Data Center SAN Switch is one example. Others include Hewlett-Packard Co.'s HP StorageWorks Multi-Protocol Router and the Brocade Multiprotocol Router (MPR).

America Online Inc. uses the Brocade MPR primarily for data migration and resource sharing across three SANs -- one for each data center in Northern Virginia. Two MPRs are stationed in each SAN, with a total of 2.5 petabytes stored.

Dan Pollack, operations architect at Dulles, Va.-based AOL, explains that when he used to migrate data from one site to another, it involved a lot of physical cabling, reconnecting and reconfiguring to establish dedicated lines for migration. Now he doesn't have to combine the fabrics to transfer data.