Method for identifying a system holding a `Reserve`

In a multi-processing environment having a plurality of systems organized as a sysplex such that said systems communicate with each other through a cross system coupling facility (XCF) and connected through a corresponding plurality of links to a control unit associated with a device and each of said links comprises a path group, wherein each of said systems gains and relinquishes access to said device by issuing a "Reserve" or "Release" command, respectively, over a corresponding one of said links to the control unit, a method of locating a particular one of the systems then holding a "reserve" for said device, said method comprising the steps of:

• determining, through any one of said systems, whether a pre-defined command previously sent to the device by said one system has successfully completed;
• issuing a reset allegiance (R/A) command by said any one system and over a corresponding one of said links connected to said one system in the event said pre-defined command has not successfully completed;
• providing, by said control unit and over said corresponding one link and in response to said R/A command, sense data comprising an identification of a particular one of said links through which said particular system holds the reserve for the device, said identification comprising an identifier for further identifying said particular one of the systems as being connected to said particular one link;
• translating the identifier into a common system name wherein said translating step comprises the steps of:
• searching through a record situated within a Coupled Dataset accessible by each of said systems through the XCF, to locate an entry containing said path group identifier contained in the sense data returned by said R/A command;
• and
• reading a common system name in said entry as the particular system then holding the reserve;
• and
• generating, in said any one system and in response to the identifier in the sense data, a message incorporating said common system name for specifying the particular system then holding the reserve, wherein said any one system is a host operating system executing on a central processing unit, a guest operating system operating on a central processing unit, or the central processing unit itself with the particular system being one of a plurality of central processing units.