Which is the correct order for evolution of mid-range storage architectures?

The correct order for the evolution of mid-range storage architectures is:

Fixed storage system configuration

Flexible hardware component configuration

Flexible software function configuration

Dual-controller active-active redundancy configuration

In the early stage, storage systems were fixed configurations with little flexibility. As technology progressed, the ability to change hardware components and software functions was added, allowing for more flexibility in the storage system. The last stage is the implementation of dual-controller active-active redundancy configuration, which provides high availability and failover capabilities in case of a hardware failure.