Microsoft launches DirectStorage for PC, a new I/O system to take full advantage of NVMe SSD


In September 2020, Microsoft announced that DirectStorage, one of the key features of the Xbox Velocity Architecture of the Xbox Series, would be available on Windows PC. It has taken a while, but finally the company keeps its promise and the DirectStorage API is now available to any developer interested in their game using this interface.

On its blog dedicated to developers, Microsoft claims that the release of the DirectStorage SDK ushers in “a new era” for faster load times and more detailed worlds in PC games. It is true that NVMe SSD storage units have been one of the great bets of the new generation of consoles, but the vast majority of PC gamers have gone through the SSD, so the jump will not be as dramatic as on PS5 or Xbox Series. However, DirectStorage’s numbers speak for themselves.

But before getting into the numbers, what is DirectStorage and how does it work? DirectStorage is a new I/O (Input/Output) system designed specifically for games to run at 100% SSD performance and hardware decompression. Today’s games stream a lot of assets to continually load what needs to be seen on screen, and DirectStorage’s job is to reduce the load on the processor when doing these I/Os. The CPU power saved can be used in other areas, such as physics, artificial intelligence, or putting more NPCs on screen.

Xbox Series mounts an NVMe SSD that delivers 2.4 GB/s of I/O performance, which can support 35,000 data I/O requests (uncompressed). Current APIs are not prepared to manage this amount of data and form a bottleneck that prevents taking advantage of all the bandwidth of the NVMe SSD, so DirectStorage’s job is to manage these operations so that they are more efficient and the CPU does not have so much work. The API also gives developers control over I/O operations.

In Xbox Series and according to Microsoft, DirectStorage has the ability to offer “immediate low-level access to more than 100 GB of data stored on the SSD for when the game requires it”. In Xbox Series everyone has an NVMe SSD with the same characteristics, but not on PC. DirectStorage is supported for Windows 10, although Microsoft recommends using Windows 11, and supports NVMe SSDs with PCIe 3.0 and PCIe 4.0 bus. Therefore, its performance may vary depending on the operating system and the type of storage.

In any case, DirectStorage won’t come to Windows PC gaming overnight. One of the first titles to use this API will be Forspoken, which last week pushed back its launch to October 11.