Methods and systems are disclosed that relate to making back-up data
available to a host server. An exemplary method includes making primary
and secondary data volumes accessible to a first server and presenting
the primary data volume and the secondary data volume to the first server
as a single virtual data volume. The secondary data volume is a copy of
the primary data volume. The method further includes directing a server
I/O request to the primary data volume if the primary data volume is
accessible or to the secondary data volume if the primary data volume is
not accessible and the secondary data volume is not reserved by a second
server.