Does anyone here use ReFS for the PVS store? I usually format the disk with NTFS and 64 KB allocation size.

Always, especially if you are versioning. Merges take just seconds.

I am. No constant reverse imaging, that's frustrating and takes ages.

I don't adjust that, just refs is fine in my testing.

We moved to ReFS for PVS store a few years ago at the last place I worked. It was wonderful for improving merge times.

Yes, always ReFS. The merge process is so much faster.

When formatting, are you using default, 4096 or 64k?

We moved to ReFS, had faster mergin times, but issues with the disk showing wrong free spaces sizes and so we moved back to NTFS

Cool - thank you for your feedback. Setup with REFS, formatted with the defaults is running smootly.