With reference to our feature on storage array virtualisation we talked to EMC. Dennis Ryan, EMC's partner sales development manager, EMEA, answered some questions that Techworld posed concerning EMC's storage array virtualisation and management product, InVista.

Techworld: EMC's InVista will run on the Cisco MDS9000 hardware. Does it support FAIS?
Dennis Ryan: FAIS is an emerging standard that is not yet finalized. EMC endorses this standard and we are heavily involved in the development. When available, EMC (and hopefully all of our switch partners) will support FAIS.

Techworld: What is EMC's position on the SANTap interface to the MDS9000?
Dennis Ryan: SANTap is primarily focused on copy services (e g remote replication). Today we do not use the SANTap part of Storage Services Interface from Cisco.

Techworld: IBM's SAN Volume Controller utilises the SANtap interface. It actually resides on a CSM module in the MDS9000 box. SANTap by itself is not sufficient for storage virtualisation. It is part of a larger solution.

Techworld: Is IBM's SVC an in-band virtualising appliance even though it runs on the Caching Services Module in MDS 9000 hardware?
Dennis Ryan: Yes, the architecture is the same. The only difference is that the appliance is housed in the MDS Director

Techworld: Does the rise of in-fabric storage intelligence mean that storage virtualisation can no longer best be handled by an out-of-band or in-band appliance with no logical connection to the fabric switches/director?
Dennis Ryan: After evaluating both in-band and out-of-band architectures, we've come to the conclusion that split-path architecture based on intelligent switches is the optimal architecture. This architecture combines the best of both worlds, without the potential bottle-necks (in-band) or host agents (out-of-band)

Techworld: How is EMC's InVista better for customers (and developers) than IBM's SVC?
Dennis Ryan: The Invista architecture provides better scalability and superior data integrity, since we do not rely on the in-band store-and-forward architecture that the SVC uses. Invista is also a more open solution that allows the customer to base his virtualisation strategy on hardware from his preferred switch vendor (Brocade, Cisco and McData)

Techworld: What is EMC's view of storage array-based virtualisation such as the products shipped by HDS (TagmaStore, NCS55) and Sun (TagmaStore and StorEdge 6920)?
Dennis Ryan: Tagmastore is a box-centric solution from a box-centric company (HDS). It has all the drawbacks of in-band solutions like SVC, but it is more proprietary and expensive. I do not know enough about the SUN solution, but SUN's storage strategy so far has not been too impressive. Will customers trust them with something as strategic as virtualisation?

Techworld: Does storage management (provisioning, monitoring, replication, etc) need a storage virtualisation layer to work on and through?
Dennis Ryan: Storage virtualisation is not a prerequisite for storage management but it will simplify management, particularly in heterogeneous environments. Storage virtualization will also allow for more storage management tasks to be carried out while the applications are running(e g moving data between storage systems).

Techworld: The Symantec view of Storage virtualisation can be read here. A terrific book on storage virtualisation by McDATA's Tom Clark is well worth reading. Additional features on IBM and Intransa views on virtualisation, also HP, will be appearing soon.