Casing exit anchor with redundant setting system

A method of setting a downhole anchor 88 comprising a first setting force generated by increasing annular pressure, sensing that the force did not set the anchor and introducing a second setting force to set the anchor without reconfiguring the anchor. The annular pressure may rupture a burst disc 174 and urge a first piston element 144 axially away from a second piston element 146 and towards a slip 89. The second setting force may be generated by increasing a pressure within a tubular supporting the anchor. The internal pressure may urge the first and second piston elements axially away from each other. If the second setting force does not set the anchor, it may be set by a third setting force generated by contacting a piston element with a surface of the wellbore and shifting another piston element with that piston element.