Windows 11 dev drive: how and why does it work?

Question

Windows 11 has a "dev drive" feature which can improve performance of developer workloads. Developer drives use ReFS.

Questions:

1. Why is using ReFS going to help performance? After all, in general, changing to a more advanced filesystem is usually not going improve performance.
2. Can we use it in other scenarios like gaming to improve performance?
3. Are there similar ideas before for linux and other OS?

Answer 1

1. Windows Dev Drives offer improved performance for development workflows due to doing less, actually. The main difference is that various filesystem filters/hooks don't run on the Dev Drive, most notably putting the Windows Defender live antivirus protection in a less hyperactive (but also less secure) operation mode. Windows Defender serializing and blocking IO is the primary source of Windows-specific IO slowness. It's not (primarily) ReFS offering the improved performance, it's the other tuning done by default for Dev Drive partitions. (It does make that tuning more practical, though, AIUI.)
2. It might help in other scenarios, but it's unlikely to. The IO performance boost is primarily in minimizing per-operation overhead, especially on parallel small file creation/writes. Games typically bundle their assets and have large chunked read patterns instead of the bursty patterns seen in development workflows.
3. Windows Dev Drive is about getting the Windows filesystem closer to the Linux filesystem performance. Linux manages its filesystem very differently from Windows, and as a result, Linux is much more performant in many-small-file developer workflows than Windows is, even when using a Dev Drive. Because Dev Drive is about tuning Windows-specific filesystem properties, the techniques used there are highly unlikely to apply to other OSes' filesystems.