Systems, methods, apparatuses, and software for data storage systems are provided herein. In one example, a data storage assembly is provided. The data storage assembly includes a plurality of storage drives each comprising a PCIe host interface and solid state storage media, with each of the storage drives configured to store and retrieve data responsive to storage operations received over an associated PCIe host interface. The data storage assembly includes a PCIe switch circuit coupled to the PCIe host interfaces of the storage drives and configured to receive the storage operations issued by a plurality of host systems over a shared PCIe interface and transfer the storage operations for delivery to the storage drives over selected ones of the PCIe host interfaces. The data storage assembly includes holdup circuitry configured to provide power to at least the storage drives after input power is lost to the data storage assembly.