You need to format (ext3, ext4) an external USB disk drive for rsnapshot to work. rsnapshot uses a "hard links" feature that is unique to Linux/Unix filesystems. "Hard Links" are not supported on filesystems such as: '''"smbfs"''', '''"Samba (SMB)"''', '''"FAT"''', '''"FAT32"''', '''"NTFS"''', '''"CIFS"''', '''"vfat"'''. Also "Amahi Greyhole" can "mount" Amahi shares that look like "local disk drives" '''''but''''' these are Samba (SMB) mounted shares.