Brocade has added an encryption switch and blade to its SAN fabric products. You can now encrypt the data in your Brocade SAN without having to use Brocade's own-brand HBAs. The company has also added encryption support to a new version of its DCFM management software and announced that both RSA and NetApp key management …
GCM is a block cipher mode of operation that provides authentication. It's not a variation of AES, but just a different way of using it. See also "Block_cipher_modes_of_operation" on Wikipedia.
The Brocade product incorporates Netapp's SEP (Secure Encryption Processor). The SEP originated from Decru, which NetApp acquired a few years ago. Decru was a start up of the CIA, and originally supported by the CIA's venture capital firm, In-Q-Tel. What's cool is that the SEP is an FPGA based processor which means it can be re-programmed if possible. If AES-256 no longer becomes the standard, a firmware update and a restart is all that's needed to upgrade the algorithm. Cisco uses ASIC based chips which can't be re-programmed.
As for the NetApp key management stuff. They follow the IEEE P1619.3 standard that has not been ratified yet. Which is why they say they'll support tape drives soon. So far no tape drive manufacturer adheres to the P1619.3 standard. They can currently manage keys from Oracle 11G.