I am setting up a Linux server (probably will be NixOS) where my VM disk files will be stored on top of an NTFS partition. (Yes I know NTFS sucks but it has to be this way.)
I am asking which guest filesystem will have the best performance for a very mixed workload. If I had access to the extra features of BTRFS or ZFS I would use them but I have no idea how CoW interacts with NTFS; that is why I am asking here.
Also I would like some NTFS performance tuning pointers.
Ntfs isn’t going to care or even be aware of the hypervisor FS, zfs or btrfs would both work fine.
Making sure you don’t have misaligned sectors, is pretty much the only major pitfall. Make sure you use paravirt storage and network drivers.
Edit: I just realized you’re asking for the opposite direction, but ultimately the same guidelines apply. It doesn’t matter what filesystems are on what, with the above caveats.