OK no SLOG then. That's good to know and makes sense. I'm throwing my VMs on an NVMe on PCIe right now and backing it up with Veeam to a ZFS share. Napp-it is also on that NVMe, so I may move it off to a SSD... I'm guessing napp-it doesn't need to be on NVMe, so putting it on SSD it can be separate from everything else in case the NVMe dies.Robocopy is fine as it can transfer Windows ntfs ACL (rsync cannot)
Ram is used for caching but caching is not filebased but based on ZFS datablocks in recsize on a read last/ read most optimazation. Perfect for random io for many users not so for media files
Beside databases or VM storage you do not want or need (mostly) sync write.