# US 2013/0159620 A1 · Storage system and method for controlling memory in storage system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0159620 A1 - Document ID: US20130159620A1 - Status: Published application - Kind: A1 - Application number: 13/380,218 - Filed: 2011-12-14 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Assignees: Hitachi, Ltd. - Inventors: Yuki Sakashita; Shintaro Kudo; Yusuke Nonaka - Web page: https://patentgrep.com/patent/US20130159620A1 ## CPC - G06F 3/0658: {Controller construction arrangements} - G06F 3/061: {Improving I/O performance} - G06F 3/0626: {Reducing size or complexity of storage systems} - G06F 3/067: {Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]} - G06F 3/0689: {Disk arrays, e.g. RAID, JBOD} - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract According to a storage system of a prior art adopting a cluster structure, various types of large-capacity memories were arranged to enhance the access performance, so that the system required a dedicated control circuit, and there was difficulty in realizing cost reduction and improvement of access performance simultaneously. In order to solve the problems, the present invention provides a storage system in which a group of memories is integrated to MPU memories directly coupled to MPUs in respective controller units, wherein each MPU memory is divided into a duplication information area and a non-duplication information area, and attribute information for controlling accesses thereto are provided. Further, each duplication information area is provided with a double master information area capable of referring to a first memory and a second memory and a single master information area capable of referring only to either the first memory or the second memory, and the accesses thereto are performed based on the attribute information. ## Claims ### Claim 1 A storage system comprising: a first controller having a first processor and a first memory coupled to the first processor and having a local area for storing information accessible only from the first processor and a shared memory area having a first area and a second area; a second controller having a second processor and a second memory coupled to the first processor and having a local area for storing information accessible only from the second processor and a shared memory area having a first area and a second area; wherein the first memory is coupled to the second processor; the second memory is coupled to the first processor; the first processor or the second processor performs duplex writing of a first control information to the first area of the first and second memories, the duplicated first control information capable of being read from both the first processor and the second processor; and the first processor or the second processor performs duplex writing of a second control information to the second area of the first and second memories, wherein only one of the duplicated second control information is permitted to be read from both the first processor and the second processor. ### Claim 2 (depends on 1) The storage system according to claim 1, wherein when the first processor updates the first control information subjected to duplex writing to the first and second memories, writing of data by the second processor to the shared area of the first and second memories is not permitted until the update is completed. ### Claim 3 (depends on 2) The storage system according to claim 2, further comprising: a plurality of disk drives and a plurality of logical units provided from the plurality of disk drives; wherein one of the first controller or the second controller is assigned as the controller for controlling an I/O with respect to the logical unit for each of the plurality of logical units; and regarding a control information unique to any one of the plurality of logical units out of the second control information, only the control information written in the first memory or the second memory of the controller assigned to said logical unit is permitted to be read from the first processor and the second processor. ### Claim 4 (depends on 3) The storage system according to claim 3, wherein an update frequency of the first control information is greater than an update frequency of the second control information. ### Claim 5 (depends on 3) The storage system according to claim 3, wherein a number of times of update of the first control information is greater than a predetermined threshold. ### Claim 6 (depends on 3) The storage system according to claim 3, wherein the first control information includes either a copy pair information of the logical unit or a system configuration information. ### Claim 7 (depends on 3) The storage system according to claim 3, wherein the second control information includes either a difference information of a copy pair of the logical unit or a statistical information. ### Claim 8 A method for controlling a storage system, the storage system comprising: a first controller having a first processor and a first memory having a local area for storing information accessible only from the first processor and a shared memory area having a first area and a second area; and a second controller having a second processor and a second memory having a local area for storing information accessible only from the second processor and a shared memory area having a first area and a second area; wherein the method comprises: performing duplex writing of a first control information to the first area of the first and second memories by the first processor or the second processor; reading either one of the duplicated first control information from both the first processor and the second processor; performing duplex writing of a second control information to the second area of the first and second memories by the first processor or the second processor; and reading only one of the duplicated second control information determined in advance from the first processor or the second processor. ### Claim 9 (depends on 8) The method for controlling a storage system according to claim 8, wherein when the first processor updates the first control information subjected to duplex writing to the first and second memories, writing of data by the second processor to the shared area of the first and second memories is not permitted until the update is completed. ### Claim 10 (depends on 9) The method for controlling a storage system according to claim 9, wherein the first controller is assigned as a controller for controlling an I/O with respect to a logical unit provided from a plurality of disk drives included in the storage system; and if the second control information is a control information unique to any one of the plurality of logical units, the first processor or the second processor reads only the second control information written in the first memory belonging to the first controller. ### Claim 11 (depends on 10) The method for controlling a storage system according to claim 10, wherein the controller assigned to the logical unit is changed from the first controller to the second controller; and after matching the contents in the first and second memories of the second control information belonging to said logical for of which the controller has been changed, the first processor or the second processor is permitted to read only the second control information written in the second memory belonging to the second controller. ### Claim 12 (depends on 11) The method for controlling a storage system according to claim 11, wherein an update frequency of the first control information is greater than an update frequency of the second control information. ### Claim 13 (depends on 11) The method for controlling a storage system according to claim 11, wherein a number of times of update of the first control information is greater than a predetermined threshold. ### Claim 14 (depends on 11) The method for controlling a storage system according to claim 11, wherein the first control information includes either a copy pair information of the logical unit or a system configuration information. ### Claim 15 (depends on 11) The method for controlling a storage system according to claim 11, wherein the second control information includes either a difference information of a copy pair of the logical unit or a statistical information.