Btrfs speed increase

I’m not sure I understand this feature. The documentation says if UrBackup detects a btrfs file system it uses a special snapshotting feature to increase performance. Does this refer to detecting btrfs on the source client that it’s backing up, or on the destination file system that the server is sending the backup to???

Doh! Just read the last part of the Server Admin manual where it says:

If UrBackup detects a btrfs filesystem it uses a special snaphotting file backup mode. It saves every file backup of every client in a separate btrfs sub-volume. When creating a incremental file backup UrBackup then creates a snapshot of the last file backup and removes, adds and changes only the files required to update the snapshot.

I guess what I need to know then is: Does this btrfs file system need to be local, or can it detect that kind of thing over any kind of network share (i.e. NFS, SAMBA, etc.) ???

It needs to be local, because UrBackup uses btrfs syscalls.