Load distribution in storage area networks

A system in communication with a plurality of I/O devices over network paths in a fabric, comprising:

• a plurality of I/O ports capable of connecting to I/O ports of the I/O devices to form network paths defining a route through the fabric between one of a plurality of I/O ports used by the system and one of a plurality of I/O ports of one of the I/O devices;
• a load balancing system executed to perform operations, the operations comprising:
• determining eligible network paths that are available to be used to communicate between the system and the I/O devices;
• selecting one of the eligible network paths based on criteria for each of the eligible network paths, comprising:
• an I/O port utilization of the I/O port for the system based on I/O resources consumed by at least one of the I/O devices assigned to the I/O port for the system;
• a network path distance based on a distance between the I/O port for the system and the I/O port on the I/O device in the network path;
• a fabric utilization indicating data rates of ports in the network path between the ports on the system and the I/O device;
• and
• using the selected network path for communication between the system and the I/O device to which the system connects on the network path.

A computer readable storage medium implementing a load balancing program for identifying a network path from a plurality of network paths between a system and a plurality of Input/Output devices, wherein each network path defines a route through a fabric between one of a plurality of I/O ports used by the system and one of a plurality of I/O ports used to communicate with one of the I/O devices, wherein the load balancing program performs operations, the operations comprising:

• determining eligible network paths that are available to be used to communicate between the system and the I/O devices;
• selecting one of the eligible network paths based on criteria for each of the eligible network paths, comprising:
• an I/O port utilization of the I/O port for the system based on I/O resources consumed by at least one of the I/O devices assigned to the I/O port for the system;
• a network path distance based on a distance between the I/O port for the system and the I/O port on the I/O device in the network path;
• a fabric utilization indicating data rates of ports in the network path between the ports on the system and the I/O device;
• and
• using the selected network path for communication between the system and the I/O device to which the system connects on the network path.

A computer readable storage medium including a load balancing program executed to identify an input/output (I/O) network path from a set of I/O network paths connecting a host system via a network to a storage subsystem, the host system comprising at least one host bus adapter (HBA), the storage subsystem comprising at least one I/O device, the network comprising at least one network device, wherein each of the HBAs, each of the I/O devices, and each of the network devices include at least one I/O port, wherein the load balancing program performs operations, the operations comprising:

• determining an HBA port limit for each of the at least one I/O port of each of the at least one HBAs;
• determining a set of I/O network paths connecting the at least one I/O port of each of the at least one HBAs via the I/O ports of the at least one network device to the at least one I/O port of each of the at least one I/O device;
• determining for each I/O network path a fabric utilization limit;
• determining an HBA port utilization for each of the at least one I/O ports of the at least one HBA based on I/O resources consumed by at least one of the I/O devices assigned to the HBA;
• discarding all network paths for which the HBA utilization is greater than the HBA port limit;
• determining a network path distance for each of the remaining network paths;
• discarding all network paths for which the network path distance is greater than the path distance limit;
• determining a fabric utilization for each of the remaining network paths;
• discarding all network paths for which the fabric utilization is greater than the fabric utilization limit;
• determining the I/O network path from the remaining network paths.