A method to control access to logical volumes. The method provides a
plurality of host computers and an information storage and retrieval
system comprising a plurality of logical volumes. The method forms (N)
host computer groups, assigns one or more of the host computers to the
(i)th host computer group, such that each host computer assigned to (i)th
host computer group is not assigned to any other of the (N) host computer
groups. The method forms (N) logical volume groups, assigns one or more
logical volumes to the (i)th logical volume group, such that each of the
logical volumes assigned to the (i)th logical volume group is not
assigned to any other of the (N) logical volume groups. The method
maintains a database associating the (i)th host computer group with the
(i)th logical volume group, and permits a host computer assigned to the
(i)th host computer group to access a logical volume assigned to the
(i)th logical volume group.