btrfs does not support lz4 compression. Unless you meant lzo, which performs terribly on incompressible data, you will want to use ZFS for lz4.<p>Also, nodatacow is a hack. If you take a snapshot on btrfs with nodatacow, it must use CoW on each thing in the snapshot that is overwritten. Until then, what ever horrible performance nodatacow prevented will manifest temporarily. ZFS is designed to make things asynchronous as much as possible (with the exception of partial record writes to unaccredited records, which needs to be fixed), so it lacks an equivalent to nodatacow and does not need it.