Scale-out adds performance by adding controller pairs, but forces unnecessary hardware spend when only capacity is needed. Combining independent scale-up and scale-out is the architecture that makes composable storage possible.

Enterprise storage has two independent requirements: capacity and performance. Scale-up-only architectures struggle to address both – hitting metadata and DRAM ceilings before either dimension is adequately satisfied.

Active/passive architecture limits a storage array to 50% of its available controller performance – and costs more per unit of throughput than a true active/active design.

When flash eliminated mechanical latency, the bottleneck moved – from the persistence layer to the controllers. Deduplication and data reduction now place crushing demands on controller CPU and DRAM.