Maintaining data integrity through power loss with operating system control

A storage controller has an operating system (OS) and power control firmware configured to manage use of battery power during a power outage event. The OS specifies to the power control firmware first and second sets of physical components that should be shed by power control firmware during a two-phase vault process. Upon a power failure, the power control firmware turns off power to the first set of physical components and notifies the OS of the power failure. The OS determines whether to abort or continue the vault process. If the OS aborts the vault process, the power control firmware restores power to the first set of physical components. If the OS continues the vault process, the power control firmware turns off power to the second set of physical components, the OS saves application state, and moves all data from volatile memory to persistent memory.