Modular PCIe: The New Face of Storage Networking?

Many storage professionals look at solid state technology and see what they want to see. For some, it is a handy high-speed cache that gives an edge to Web transaction and financial applications. Others see an entirely new storage tier to supplement existing disk-based infrastructure. And some see a completely new forms of modular compute/storage infrastructure that will power new generations of low-cost, cloud-based services.

In previous posts, I’ve mentioned that these modular platforms would do away with the SAN altogether because they would link resources through high-speed PCIe links rather than iSCSI or Fibre Channel networks and all the complexity and capital investment they entail.

So far, the only two drawbacks are the relatively short range of most PCIe architectures and the lack of advanced SAN features like deduplication and thin provisioning. After all, PCIe is more of an interconnect than a storage interface, deployed usually in desktop, laptop or server configurations.

But as the saying goes, times change. In modular configurations like Nutanix’ Complete Cluster, the need for long-haul storage connections is diminished because the modular server/storage units can be packed fairly close together. Still, it’s not inconceivable that some architectures will require a certain amount of space between clusters, and as more units are added latency will likely increase as data has to navigate its way through multiple PCIe links.

That’s why it’s interesting to note that there are movements afoot to ferry PCIe across optical cables. Apple and Intel are working on an optical version of the Thunderbolt interconnect, which Intel has already vowed will feature a PCIe 3.0 interface before year’s end. The intent is to provide a much faster transfer rate than current USB 3.0 technology, but optical technology also presents an opportunity to send signals over greater distances without degradation, something that modular systems could make great use of.

As far as management features go, it’s true that the vast majority of PCIe capabilities center around boosting I/O performance rather than streamlining data volumes. But most of those tools are designed to ease the strain that Big Data is placing on legacy storage environments. Modular systems are more at home in the cloud, however, where resource constraints are not as problematic. And it seems likely that many SAN features can be replicated on the virtual layer anyway, as Quantum Corp. has done with its new DXi V1000 virtual dedupe appliance.

So, does this mean that the SAN is finished? Not likely. There’s too much investment at stake to simply chuck it in the bin. But it does mean that there is a low-cost alternative to expensive SAN infrastructure as enterprises face the twin tasks of expanding resources and restraining costs.

Arthur Cole covers networking and the data center for IT Business Edge. He has served as editor of numerous publications covering everything from audio/video production and distribution, multimedia and the Internet to video gaming.

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