Microsoft has announced that its DirectStorage API will be compatible with both PCIe 3.0 as well as PCIe 4.0 based SSDs. This means faster loading times and reduced load on the CPU in the case of titles using high-resolution textures and assets, thanks to modern graphics architectures. This can be understood by having a looking at NVIDIA’s RTX I/O feature which is essentially hardware-level support for the same API:
DirectStorage API basically transfers the job of compression-decompression of assets from the CPU to the GPU which is a more efficient approach due to its parallel nature. In addition to this, DirectStorage also helps send batch I/O requests while earlier every I/O request big or small was individually sent, adding unnecessary load to the processor.
Together with Sampler Feedback, this significantly reduces the load not only on the graphics memory but also cuts down the time spent on I/O cycles while also reducing the bandwidth requirements of the game.
It’s important to note that SATA-based SSDs aren’t supported and an NVMe interface is required to leverage the feature. Furthermore, while PCIe 3.0 drives are supported, the advantages of a 4.0 drive will be much more apparent.