# US 2020/0045108 A1 · Controlling the state of duplexing of coupling facility structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0045108 A1 - Document ID: US20200045108A1 - Status: Published application - Kind: A1 - Application number: 16/653,602 - Filed: 2019-10-15 - Published: 2020-02-06 - Earliest claimed: 2001-10-01 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: David A. Elko; Steven N. Goss; Michael J. Jordan; Georgette L. Kurdt; Jeffrey M. Nick; Kelly B. Pushong; David H. Surman - Web page: https://patentgrep.com/patent/US20200045108A1 ## CPC - G06F 11/2007: {using redundant communication media} - G06F 11/2028: {eliminating a faulty processor or activating a spare} - G06F 11/2097: {maintaining the standby controller/processing unit updated (initialisation or re-synchronisation thereof G06F11/1658 and subgroups)} - H04B 1/74: for increasing reliability, e.g. using redundant or spare channels or apparatus {(replacing by standby devices for amplifiers H03F1/52, H03F1/542)} - H04L 1/22: using redundant apparatus to increase reliability - H04L 5/14: Two-way operation using the same type of signal, i.e. duplex - H04L 41/50: Network service management, e.g. ensuring proper service fulfilment according to agreements - H04L 67/108: {characterised by resources being split in blocks or fragments} - H04L 67/1095: Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes - H04L 67/568: Storing data temporarily at an intermediate stage, e.g. caching - Y10S 707/99938: Concurrency, e.g. lock management in shared database - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 2) 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. ### Claim 4 (depends on 3) 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. ### Claim 5 (depends on 1) 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. ### Claim 6 (depends on 5) 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. ### Claim 7 (depends on 1) The computer program product of claim 1, wherein the coupling facility structure is a cache structure. ### Claim 8 (depends on 7) 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. ### Claim 9 (depends on 1) The computer program product of claim 1, wherein the coupling facility structure is a list structure. ### Claim 10 (depends on 9) 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. ### Claim 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. ### Claim 12 (depends on 11) 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. ### Claim 13 (depends on 11) 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. ### Claim 14 (depends on 11) The computer system of claim 11, wherein the coupling facility structure is a cache structure. ### Claim 15 (depends on 11) The computer system of claim 11, wherein the coupling facility structure is a list structure. ### Claim 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. ### Claim 17 (depends on 16) The computer-implemented method of claim 16, further comprising resetting a duplexing active indicator for the coupling facility structure, based on breaking duplexing. ### Claim 18 (depends on 16) 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. ### Claim 19 (depends on 16) The computer-implemented method of claim 16, wherein the coupling facility structure is a cache structure. ### Claim 20 (depends on 16) The computer-implemented method of claim 16, wherein the coupling facility structure is a list structure.