Controlling the state of duplexing of coupling facility structures

Abstract

A coupling facility is coupled to one or more other coupling facilities via one or more peer links. The coupling of the facilities enables various functions to be supported, including the duplexing of structures of the coupling facilities. Duplexing is performed on a structure basis, and thus, a coupling facility may include duplexed structures, as well as non-duplexed or simplexed structures.

What is claimed is: 
     
         1 . A computer program product for managing the state of duplexing of coupling facility structures, said computer program product comprising:
 a computer readable storage medium readable by a processing circuit and storing instructions for performing a method comprising:
 detecting that a connection between a first coupling facility having a first instance of a coupling facility structure and a second coupling facility having a second instance of the coupling facility structure has failed; 
 determining whether another connection exists between the first coupling facility and the second coupling facility; 
 preserving duplexing of the coupling facility structure, based on determining that another connection exists; and 
 breaking duplexing of the coupling facility structure, based on determining that another connection does not exist. 
   
     
     
         2 . The computer program product of  claim 1 , wherein the method further comprises resetting a duplexing active indicator for the coupling facility structure, based on breaking duplexing. 
     
     
         3 . The computer program product of  claim 2 , wherein the duplexing active indicator is located in a vector, the vector comprising a plurality of positions for a plurality of structures. 
     
     
         4 . The computer program product of  claim 3 , wherein the vector is indexed by a structure identifier for the coupling facility structure to locate the duplexing active indicator to be reset. 
     
     
         5 . The computer program product of  claim 1 , wherein the method further comprises selecting the first instance of the coupling facility structure or the second instance of the coupling facility structure to continue to support command execution, based on breaking duplexing of the coupling facility structure. 
     
     
         6 . The computer program product of  claim 5 , wherein the method further comprises deallocating the first instance of the coupling facility structure or the second instance of the coupling facility structure not selected to continue to support command execution. 
     
     
         7 . The computer program product of  claim 1 , wherein the coupling facility structure is a cache structure. 
     
     
         8 . The computer program product of  claim 7 , wherein the cache structure includes one or more cache structure objects, the one or more cache structure objects including a duplexing state object that indicates a duplexing state for the cache structure. 
     
     
         9 . The computer program product of  claim 1 , wherein the coupling facility structure is a list structure. 
     
     
         10 . The computer program product of  claim 9 , wherein the list structure includes one or more list structure objects, the one or more list structure objects including a duplexing state object that indicates a duplexing state for the list structure. 
     
     
         11 . A computer system for managing the state of duplexing of coupling facility structures, said computer system comprising:
 a memory; and   a processor in communication with the memory, wherein the computer system is configured to perform a method, said method comprising:
 detecting that a connection between a first coupling facility having a first instance of a coupling facility structure and a second coupling facility having a second instance of the coupling facility structure has failed; 
 determining whether another connection exists between the first coupling facility and the second coupling facility; 
 preserving duplexing of the coupling facility structure, based on determining that another connection exists; and 
 breaking duplexing of the coupling facility structure, based on determining that another connection does not exist. 
   
     
     
         12 . The computer system of  claim 11 , wherein the method further comprises resetting a duplexing active indicator for the coupling facility structure, based on breaking duplexing. 
     
     
         13 . The computer system of  claim 11 , wherein the method further comprises selecting the first instance of the coupling facility structure or the second instance of the coupling facility structure to continue to support command execution, based on breaking duplexing of the coupling facility structure. 
     
     
         14 . The computer system of  claim 11 , wherein the coupling facility structure is a cache structure. 
     
     
         15 . The computer system of  claim 11 , wherein the coupling facility structure is a list structure. 
     
     
         16 . A computer-implemented method of managing the state of duplexing of coupling facility structures, said computer-implemented method comprising:
 detecting that a connection between a first coupling facility having a first instance of a coupling facility structure and a second coupling facility having a second instance of the coupling facility structure has failed;   determining whether another connection exists between the first coupling facility and the second coupling facility;   preserving duplexing of the coupling facility structure, based on determining that another connection exists; and   breaking duplexing of the coupling facility structure, based on determining that another connection does not exist.   
     
     
         17 . The computer-implemented method of  claim 16 , further comprising resetting a duplexing active indicator for the coupling facility structure, based on breaking duplexing. 
     
     
         18 . The computer-implemented method of  claim 16 , further comprising selecting the first instance of the coupling facility structure or the second instance of the coupling facility structure to continue to support command execution, based on breaking duplexing of the coupling facility structure. 
     
     
         19 . The computer-implemented method of  claim 16 , wherein the coupling facility structure is a cache structure. 
     
     
         20 . The computer-implemented method of  claim 16 , wherein the coupling facility structure is a list structure.