Coho is describing itself as neither a software-defined networking (SDN) company nor a flash-memory play. The latter case would be untruthful (Coho’s appliances include disk drives as well as flash) and the former isn’t what Coho is aiming for. The startup is a software company trying to make enterprise storage as fluid as computing resources are in the cloud, says Andrew Warfield, the company’s CTO and co-founder.
Really, Coho’s heritage is in server virtualization, as the founders include key figures behind the Xen hypervisor — CEO Ramana Jonnala and Chief Architect Keir Fraser. Fraser was Xen’s principal author and continues to be its lead maintainer, according to his online bio.
Coho’s box, the Datastream 1000, is a 2U server appliance that includes commodity flash (from Intel) and disk drives, along with two 10-Gb/s interfaces. Coho also provides an off-the-shelf switch with 48 10-Gb/s ports, which sends data to the microarrays as if they were one big storage pool — that’s where the SDN-like part comes in. (Warfield indicated the switch currently comes from Arista.)
Coho makes some storage decisions within the microarrays as well. “We are able to analyze the live workloads and keep the hot data in flash while getting the economics of moving the cold data to disks,” Warfield says.
With this architecture, Coho claims, storage can scale up linearly by adding more microarrays. That’s in contrast to normal enterprise storage, which is sold in monolithic arrays that get replaced every five years or so, Warfield says.
As of last week, Warfield expected Coho’s products to reach general availability just after Tuesday’s announcement.