Yes, and this is also the biggest challenge. Right now we use XFS to enable CoW, but that quickly leads to filesystem fragmentation. I'm still looking at a way

Yes, and this is also the biggest challenge. Right now we use XFS to enable CoW, but that quickly leads to filesystem fragmentation. I'm still looking at a way that we can quickly let both VM A and VM B use the same base snapshot, and write new changes to either anonymous memory or a file.