# US 2014/0157046 A1 · Techniques for dynamically tracking logical units moving between input/output ports of a storage area network target > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0157046 A1 - Document ID: US20140157046A1 - Status: Published application - Kind: A1 - Application number: 13/690,129 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corp - Inventors: KIRAN KUMAR ANUMALASETTY; PHANI KUMAR AYYAGARI; SUDHIR MADDALI; RAMESH KUMAR MARUPAKA; SANKET RATHI - Web page: https://patentgrep.com/patent/US20140157046A1 ## CPC - G06F 11/2007: {using redundant communication media} - G06F 11/2005: {using redundant communication controllers} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A technique for operating a storage area network includes detecting an input/output operation failure associated with a logical unit number, which is associated with a first target port. The technique also includes determining, subsequent to the detected input/output operation failure, whether the logical unit number is associated with a second target port. Finally, the technique includes routing subsequent input/output operations for the logical unit number to the logical unit number via the second target port, in response to determining that the logical unit number is associated with the second target port. ## Claims ### Claim 1 A method of operating a storage area network, comprising: detecting, by a data processing system, an input/output operation failure associated with a logical unit number, wherein the logical unit number is associated with a first target port; determining, by the data processing system, whether the logical unit number is associated with a second target port subsequent to the detected input/output operation failure; and routing, by the data processing system, subsequent input/output operations for the logical unit number to the logical unit number via the second target port in response to determining that the logical unit number is associated with the second target port. ### Claim 2 (depends on 1) The method of claim 1, wherein the determining, by the data processing system, whether the logical unit number is associated with a second target port further comprises: determining, by the data processing system, a first identifier of a target associated with the first target port; issuing, by the data processing system, a report logic unit number query to one or more target ports with the first identifier; receiving, by the data processing system, one or more logical unit number identifiers in response to the report logic unit number query; issuing, by the data processing system, a device identifier inquiry for the one or more logical unit number identifiers reported; receiving, by the data processing system, one or more device identifiers in response to the device identifier inquiry; and comparing a device identifier of the logical unit number to the one or more device identifiers received, wherein when the device identifier matches one of the one or more device identifiers received the logical unit number is associated with the second target port. ### Claim 3 (depends on 2) The method of claim 2, wherein the first identifier is a world wide node number. ### Claim 4 (depends on 2) The method of claim 2, wherein the device identifiers are device serial numbers. ### Claim 5 (depends on 1) The method of claim 1, wherein the first and second target ports are associated with a same storage area network target. ### Claim 6 (depends on 1) The method of claim 1, wherein the first and second target ports are respective ports of a redundant array of inexpensive disks array. ### Claim 7 (depends on 1) The method of claim 1, wherein the first and second target ports are respective ports of a hard disk drive array of a storage area network. ### Claim 8 A computer program product, comprising: a computer-readable storage medium; and computer-readable code for tracking logical unit numbers between input/output ports of storage area network targets embodied on the computer-readable storage medium, wherein the computer-readable code, when executed by a processor of a data processing system, causes the processor to: detect an input/output operation failure associated with a logical unit number, wherein the logical unit number is associated with a first target port; determine whether the logical unit number is associated with a second target port subsequent to the detected input/output operation failure; and route subsequent input/output operations for the logical unit number to the logical unit number via the second target port in response to determining that the logical unit number is associated with the second target port. ### Claim 9 (depends on 8) The computer program product of claim 8, wherein the computer-readable code, when executed by the processor of the data processing system, further causes the processor to: determine a first identifier of a target associated with the first target port; issue a report logic unit number query to one or more target ports with the first identifier; receive one or more logical unit number identifiers in response to the report logic unit number query; issue a device identifier inquiry for the one or more logical unit number identifiers reported; receive one or more device identifiers in response to the device identifier inquiry; and compare a device identifier of the logical unit number to the one or more device identifiers received, wherein when the device identifier matches one of the one or more device identifiers received the logical unit number is associated with the second target port. ### Claim 10 (depends on 9) The computer program product of claim 9, wherein the first identifier is a world wide node number. ### Claim 11 (depends on 9) The computer program product of claim 9, wherein the device identifiers are device serial numbers. ### Claim 12 (depends on 8) The computer program product of claim 8, wherein the first and second target ports are associated with a same storage area network target. ### Claim 13 (depends on 8) The computer program product of claim 8, wherein the first and second target ports are respective ports of a redundant array of inexpensive disks array. ### Claim 14 (depends on 8) The computer program product of claim 8, wherein the first and second target ports are respective ports of a hard disk drive array of a storage area network. ### Claim 15 A data processing system, comprising: a memory system; and a processor coupled to the memory system, wherein the processor is configured to: detect an input/output operation failure associated with a logical unit number, wherein the logical unit number is associated with a first target port; determine whether the logical unit number is associated with a second target port subsequent to the detected input/output operation failure; and route subsequent input/output operations for the logical unit number to the logical unit number via the second target port in response to determining that the logical unit number is associated with the second target port. ### Claim 16 (depends on 15) The data processing system of claim 15, wherein the processor is further configured to: determine a first identifier of a target associated with the first target port; issue a report logic unit number query to one or more target ports with the first identifier; receive one or more logical unit number identifiers in response to the report logic unit number query; issue a device identifier inquiry for the one or more logical unit number identifiers reported; receive one or more device identifiers in response to the device identifier inquiry; and compare a device identifier of the logical unit number to the one or more device identifiers received, wherein when the device identifier matches one of the one or more device identifiers received the logical unit number is associated with the second target port. ### Claim 17 (depends on 16) The data processing system of claim 16, wherein the first identifier is a world wide node number. ### Claim 18 (depends on 16) The data processing system of claim 16, wherein the device identifiers are device serial numbers. ### Claim 19 (depends on 15) The data processing system of claim 15, wherein the first and second target ports are associated with a same storage area network target. ### Claim 20 (depends on 15) The data processing system of claim 15, wherein the first and second target ports are respective ports of a hard disk drive array of a storage area network.