Storage network system, host computer and physical path allocation method

A storage network system, comprising:

• a host computer;
• and
• a plurality of storage subsystems connected to the host computer via a network, the storage network system being capable of copying data stored in a logical volume in a storage subsystem into a logical volume in another storage subsystem,
• wherein said host computer checks a copy type and a pair status of and copy mode change expectation information about a volume pair belonging to a group to which a source logical volume belongs, and transmits to said network subsystems via the network an instruction to exclusively allocate a physical path for said volume pair to a logical path, which is a virtual communication link, for the volume pair belonging to said group if said copy mode change expectation information exceeds an allowable value previously individually specified for the group, and said storage subsystems perform allocation of a logical path in accordance with said instruction.

A host computer that is connected to a plurality of storage subsystems via a network and is capable of copying data stored in a logical volume in a storage subsystem into a logical volume in another storage subsystem, comprising:

• an interface connected to the network;
• and
• a control section connected to said interface,
• wherein said control section checks a pair status of a volume pair, which is a pair of a source logical volume and a target logical volume that is established between a source storage subsystem and a target storage subsystem, determines a coefficient value uniquely determined from said pair status as a load value of the volume pair, determines, for each group consisting one or more volume pairs, a sum of the load values of the volume pairs in the group as a group load value, and transmits to said storage subsystems via the network an instruction to allocate a number of physical paths corresponding to said group load value and a plural-group load value, which is a sum of the load values of a plurality of groups, to the volume pairs belonging to said group as a logical path, which is a virtual communication link.