The present invention provides a computer implemented method and apparatus for unmounting file systems from a plurality of file servers. The method comprises of issuing an unmount command targeting a file system of a first server among the plurality of file servers. The timeout period is then expired without receiving an unmount acknowledgement associated with the unmount command. Thus, the timeout period is associated with an allowable time for the file system to acknowledge unmounting. In response to expiring the timeout period, a ping is transmitted to the first server among the plurality of file servers. The ping timeout then expires based on a failure to receive a ping acknowledgment corresponding to the ping. This action marks the first server for a later retry of unmounting to form a marked set based on the first server.