EqualLogic provides iSCSI SAN storage. It also has virtualisation facilities. This interview forms another in our series of articles on virtalisation. Previous ones have looked at EMC, IBM, Intransa and Symantec. In this interview Techworld asked Eric Schott, director of product management at EqualLogic, some questions about EqualLogic's approach to SAN virtualization

Techworld: How does FC SAN storage virtualization and applications layered on top of it differ from iSCSI SAN virtualization and apps layered on top of it?
Eric Schott: In a Fibre Channel (FC) SAN, security and control resides in the network, so it makes sense for FC SANs to adopt a network-centric model for virtualization. The network already runs specialized switches, so adding further to the specialization does not change the nature of the overall configuration. With iSCSI SANs, security and control is in the end points while the ubiquitous Ethernet network serves as a transport, so virtualization must reside with security and control. In the case of EqualLogic’s PS Series arrays, for example, virtualization is an integral component of the storage management capabilities built into the controller of each array.

Techworld: Should SAN storage array virtualization and associated management be located in the SAN network fabric or in storage arrays or in special controllers sited between the fabric and arrays?
Eric Schott: The network-centric model of FC SANs is not a natural fit for iSCSI, since the network is not the security mechanism in iSCSI SANs. In our experience, it made the most sense to build virtualization into the array and to allow multiple arrays to work together as one storage pool in order to create the ease of use and automation we wanted to bring to the user. This allows the network to remain ubiquitous and fully interoperable. We believe that the scale of iSCSI SANs will be much greater than FC SANs, and for large-scale SANs it is inefficient and needlessly complex to build virtualization into the network. Specialized network infrastructure will result in more complexity for IT – more expensive infrastructure, high training requirements for staff, and higher operating costs.

Techworld: What does EqualLogic think of FAIS? Will EqualLogic support FAIS?
Eric Schott: FAIS is a Fibre Channel standard based on network-centric security and access control, and as such it is not appropriate for iSCSI SANs. EqualLogic believes in simplifying storage, which is why we chose iSCSI as the transport protocol for our intelligent SAN solution. FAIS may work fine in the FC world in the future, but from our point of view it is another symptom of FC’s complexity.

Techworld: Will EqualLogic support SAN array virtualization and SAN provisioning and management carried out on a FC SAN fabric hardware entity?
Eric Schott: We would rather not discuss our future product plans.

Techworld: Could you describe the storage array virtualization, and storage management facilities layered on top of that, in the EqualLogic IP SAN systems?
Eric Schott: EqualLogic has designed virtualization into each PS Series storage array in order to facilitate the ease of storage management that is our primary goal. We implement virtualization in order to simplify cumbersome tasks, such as allocating storage, load balancing, configuring RAID, and backing up and restoring data. Optimally, the physical disks and complex underpinnings of the storage are concealed from administrators and servers. Early generation virtualization products provide flexibility, but they are essentially consolidated storage solutions that do little to reduce complexity. Some actually increase the number of components to manage, while load balancing, RAID configuration, and provisioning remain difficult, manual operations. The PS Series family is designed to provide a scalable pool of storage, in addition to technology that hides the underlying configuration, regardless of its complexity.

Techworld: Is it possible, feasible and/or desirable for enterprises to have one SAN management facility including both FC and iSCSI SANs? Does or will EqualLogic provide this?
Eric Schott: Anything is possible, but the feasibility of any desirable solution comes down to economics – how much would such a management facility cost, and who will be willing to pay for it? More important, how much complexity would it introduce? Today, managing multiple FC SANs from a single console is a challenge, and I know of no affordable solution that does that well today. Creating a single tool for managing FC and iSCSI SANs is even more challenging – and there is a tremendous risk of introducing more complexity due to the fundamental differences in network philosophy.

Techworld: Is there a danger that FC SANs and iSCSI SANs will require separate and different virtualization and management facilities leading to separate islands of SAN management?
Eric Schott: I don’t know about the danger of this scenario, but it is certainly probable given the inherent differences of FC and iSCSI technologies that are not well understood by most people.

Techworld: Is EqualLogic SAN storage virtualization supportive of multi-vendor drive arrays?
Eric Schott: In order to make our SANs as easy to use a possible, we have built virtualization directly into the array where it transparently facilitates ease of management throughout all of the PS Series arrays. Virtualization is not an overlay application, but an integrated, distributed service that forms the foundation of the single scalable pool of storage that is the hallmark of an EqualLogic SAN.

Techworld: How does EqualLogic's SAN virtualization and management approach differ from suppliers such as NetApp, Intransa, FalconStor and Left-Hand Networks?
Eric Schott: EqualLogic’s PS Series SAN solution has won awards on the strength of its visionary simplicity and ease of use. In our experience, customers want simplicity and ease of use, not a component technology, which is why EqualLogic has satisfied over 600 customers in just a little over two years of shipping the PS Series. The PS Series includes everything needed to consolidate data into a single reliable pool of storage, manage and scale the storage as needed, and protect it with built-in backup and replication capabilities. No other solution, iSCSI or Fibre Channel, offers the elegant simplicity and automation of the PS Series, which has dominated comparative reviews in the categories of feature set, management, performance, reliability, and scalability against EMC, NetApp, and other vendors. Unlike other solutions, the PS Series masks complexity while automating tedious manual processes without sacrificing performan

And so...
EqualLogic uses its own arrays in its products. Intransa uses its. In these very early days of iSCSI SAN virtualisation it is naive to expect inter-operability and multi-vendor virtualisation. It's taken several goes at virtualisation in the Fibre Channel world for this to happen.

This leads us to hope that the SNIA will address IP SANs and encourage some kind of interoperability, based on standards, to emerge. This must be 12-24 months in the future though, in so far as a deliverable standard specification is concerned.

Thirdly, in the SME world into which iSCSI SANs are targeted there is a tremendous, and welcome, emphasis on simplicirty, both of implementation and of management. The total management burden for iSCSI SANs should be considerably less than for Fibre Channel SANs.

Finally, there is nothing here to weaken a view that the iSCSI and Fibre Channel SAN worlds are divergent, with different products being used for storage array virtualisation and management. Whereas interoperability in the Fibre Channel world is moderately well advanced (thank you SNIA) it is signally absent from the iSCSI SAN sphere.

But this is only to be expected. The technology is in its first flush of youth and the suppliers are going though intense bouts of engineering creativity to bring the first products to market.