System and method for dynamically assigning I/O priority

A program storage device readable by a machine, tangibly embodying a program of instructions executable by a machine to perform method steps for assigning I/O priority by one of a plurality of initiator devices in an open system, an initiator device in an open system being a host system which uses command descriptor blocks to access fixed block devices on logical units, said method comprising:

• receiving at a device driver of said one of said plurality of initiator devices, a datapath command for setting a default I/O priority for a specified logical unit, said default I/O priority value being specific to an application at said one of said plurality of initiator devices;
• parsing said datapath command to determine said default I/O priority value;
• storing said default I/O priority value for said logical unit to a priority store of a storage controller on said logical unit;
• exiting said datapath command;
• and
• operating said storage controller to access said priority store and process I/O requests from said one of said plurality of initiator devices in accordance with said default I/O priority value.

A program storage device readable by a machine, tangibly embodying a program of instructions executable by a machine to perform method steps for dynamically establishing and controlling I/O priority by a storage controller for a plurality of initiators, comprising:

• receiving at said storage controller an I/O command from an initiator selectively including an I/O priority default value for a logical unit set by a given one of said plurality of initiators, an initiator being a host system which uses command descriptor blocks to access fixed block devices on logical units, said I/O priority default value being specific to a first application at said given one of said plurality of initiators;
• responsive to said I/O command being a set default value I/O command, storing said I/O priority default value at said storage controller for thereafter processing data transfer commands from said given one of said plurality of initiator for said logical unit;
• and
• responsive to said I/O command being a data transfer command with respect to said given logical unit, queuing said data transfer command from said given one of said plurality of initiators for execution based on said I/O priority default value previously stored for said logical unit.

A computer program product for effecting data transfer in a system including a plurality of host initiators in a system including disparate host initiators and at least one storage controller according to the method comprising:

• receiving at a device driver of a given host initiator, a datapath command for setting a default I/O priority for a specified logical unit, said default I/O priority being specific to a first application at said given host initiator;
• parsing said datapath command and storing said default I/O priority for I/O commands from said given host initiator directed to said logical unit to a priority store of a storage controller on said logical unit;
• exiting said datapath command;
• issuing as a command distinct from said datapath command to said storage controller a data transfer command;
• receiving at said storage controller an I/O command from said given host initiator;
• responsive to said I/O command being a set default value I/O command, storing said I/O priority default value for data transfer commands directed from said given host initiator to said logical unit;
• and
• responsive to said I/O command being a data transfer command with respect to said logical unit, queuing said data transfer command for execution based on said I/O priority default value previously stored for data transfer commands directed from said given host initiator to said logical unit.