This will break down how to use LVM and thin-provisioned LVs in front of a disk image file allowing new writes to go to a separate LV from the original image. This will function similarly to something like UnionFS but using the LVM layer instead and using an thin provisioned LV for the new data itself. This might be useful when you already have a filesystem image (maybe from a backup or similar) and it’s big enough that copying it before using it is not feasible, but you still want to be able to revert to the previous state if something blows up. This will handle all of that at the block layer. My main use-case for this is on an older system where some of the modern union or overlay filesystems (unionfs, overlayfs, aufs, etc) are not available or stable. I’m sure there may be other uses as well, […]