# US 2020/0401605 A1 · Ability to vary on and vary off databases simultaneously across two systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0401605 A1 - Document ID: US20200401605A1 - Status: Published application - Kind: A1 - Application number: 16/448,401 - Filed: 2019-06-21 - Published: 2020-12-24 - Earliest claimed: 2019-06-21 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Scott D. HELT; Kiswanto THAYIB; Kristopher C. WHITNEY; Philip M. ALBU - Web page: https://patentgrep.com/patent/US20200401605A1 ## CPC - G06F 16/273: {Asynchronous replication or reconciliation} - G06F 12/1009: using page tables, e.g. page table structures - G06F 12/12: Replacement control - G06F 12/0804: with main memory updating (G06F12/0806 takes precedence) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Embodiments of the present disclosure provide techniques to vary on and vary off databases simultaneously across a pair of nodes in a mirroring environment. A dual vary off operation is initiated at a first node of the pair of nodes, the dual vary off operation to be performed on copies of a database respectively stored on the pair of nodes, the operation to be performed in tandem with the second node. At the first node the copy of the database stored on the first node is informed of the dual vary off operation, and an operating system of the first node is also informed of the dual vary off operation. Upon receipt at the first node of an indication from the second node that it has completed its vary off operation, the first node completes the dual vary off operation. An analogous technique is performed for a dual vary on operation. ## Claims ### Claim 1 A method comprising: initiating, at a first node of a pair of nodes in a mirroring environment, a dual vary off operation of a database, a copy of the database stored on each of the first node of the pair of nodes and a second node of the pair of nodes, the operation to be performed in tandem with the second node; and at the first node: informing the copy of the database stored on the first node of the dual vary off operation; informing an operating system of the dual vary off operation; waiting for an indication from the second node that it has completed its vary off operation; and in response to the indication from the second node, completing the dual vary off operation. ### Claim 2 (depends on 1) The method of claim 1, further comprising: receiving a user command at the first node to initiate the dual vary off operation. ### Claim 3 (depends on 1) The method of claim 1, wherein the dual vary off operation further comprises: determining, at the first node, if there are pending jobs using the database on either of the nodes; and in response to the determination, posting a message on the first node advising owners of pending jobs on either node to either cancel the dual vary off operation or to continue with it. ### Claim 4 (depends on 3) The method of claim 3, further comprising including in the message an indication that if the dual vary off operation is continued, all pending jobs using the database will be canceled. ### Claim 5 (depends on 1) The method of claim 1, wherein the pair of nodes are mirrored in a Db2 mirroring environment. ### Claim 6 (depends on 1) The method of claim 1, wherein the database is an independent auxiliary storage pool (IASP). ### Claim 7 (depends on 1) The method of claim 1, wherein completing the dual vary off operation further comprises informing the database to end system tasks that support mirroring of the database between the pair of nodes. ### Claim 8 (depends on 1) The method of claim 1, wherein completing the dual vary off operation further comprises flushing all changed pages of the database in main memory to disk. ### Claim 9 A system, comprising: one or more computer processors; and a memory containing a program which when executed by the one or more computer processors performs an operation, the operation comprising: initiating, at a first node of a pair of nodes in a mirroring environment, a dual vary off operation of a database, a copy of the database being stored on each of the first node of the pair of nodes and a second node of the pair of nodes, the operation to be performed in tandem with the second node; and at the first node: informing the copy of the database stored on the first node of the dual vary off operation; informing an operating system of the dual vary off operation; waiting for an indication from the second node that it has completed its vary off operation; and in response to the indication from the second node, completing the dual vary off operation. ### Claim 10 (depends on 9) The system of claim 9, the operation further comprising: receiving a user command at the first node to initiate the dual vary off operation. ### Claim 11 (depends on 9) The system of claim 9, the operation further comprising: determining, at the first node, if there are pending jobs using the database on either of the nodes; and in response to the determination, posting a message on the first node advising owners of pending jobs on either node to either cancel the dual vary off operation or to continue with it. ### Claim 12 (depends on 11) The system of claim 11, wherein completing the dual vary off operation further comprises informing the database to end system tasks that support mirroring of the database between the pair of nodes. ### Claim 13 (depends on 11) The system of claim 11, wherein completing the dual vary off operation further comprises flushing all changed pages of the database in main memory to disk. ### Claim 14 (depends on 9) The system of claim 9, wherein the pair of nodes are mirrored in a Db2 mirroring environment. ### Claim 15 A computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code executable by one or more computer processors to perform an operation comprising: receiving, at a first node of a pair of nodes in a mirroring environment, a dual vary on command indicating to perform a vary on operation on a database in tandem with a second node of the pair of nodes; informing a second node of the pair of nodes to initiate dual vary on processing; receiving an indication from the second node to continue with the dual vary on processing; waiting for an indication from the second node that it is ready to complete the dual vary on operation; and in response to the indication from the second node, completing the dual vary on operation. ### Claim 16 (depends on 15) The computer-readable storage medium of claim 15, wherein the database is an IASP that is stored on each of the first node and the second node. ### Claim 17 (depends on 16) The computer-readable storage medium of claim 16, the operation further comprising: accessing a replication state of the IASP on the first node and passing that state value to the second node. ### Claim 18 (depends on 16) The computer-readable storage medium of claim 16, wherein the indication received from the second node that it is ready to complete the dual vary on operation includes an indication that the second node is ready to change a state of the IASP on the second node to available. ### Claim 19 (depends on 15) The computer-readable storage medium of claim 15, the operation further comprising: upon receiving the indication from the second node to continue with the dual vary on processing, informing an operating system of the first node that a dual vary on operation has been initiated. ### Claim 20 (depends on 15) The computer-readable storage medium of claim 15, wherein, as part of completing the dual vary on processing, the operation further comprises: changing a state of the IASP on the first node to available.