Consistent point-in-time copy of a consistent asynchronous mirror target without pausing a consistent asynchronous mirror copy

A computer program product, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code executable by at least one processor to perform:

• performing a consistent asynchronous mirror copy that includes an asynchronous mirror copy from a primary volume to a secondary volume and a point-in-time copy from the secondary volume to a tertiary volume;
• receiving an initiation of a point-in-time establish from the secondary volume to an accessible consistent copy volume to start a point-in-time relationship for a point-in-time copy from the secondary volume to the accessible consistent copy volume;
• creating a target data structure for the accessible consistent copy volume with target data structure indicators set to one;
• and
• in response to copying each track from one of the secondary volume and the tertiary volume to the accessible consistent copy volume, updating a target data structure indicator for the track to zero in the target data structure for the accessible consistent copy volume.

A computer system, comprising:

• one or more processors, one or more computer-readable memories and one or more computer-readable, tangible storage devices;
• and
• program instructions, stored on at least one of the one or more computer-readable, tangible storage devices for execution by at least one of the one or more processors via at least one of the one or more memories, to perform operations comprising:
• performing a consistent asynchronous mirror copy that includes an asynchronous mirror copy from a primary volume to a secondary volume and a point-in-time copy from the secondary volume to a tertiary volume;
• receiving an initiation of a point-in-time establish from the secondary volume to an accessible consistent copy volume to start a point-in-time relationship for a point-in-time copy from the secondary volume to the accessible consistent copy volume;
• creating a target data structure for the accessible consistent copy volume with target data structure indicators set to one;
• and
• in response to copying each track from one of the secondary volume and the tertiary volume to the accessible consistent copy volume, updating a target data structure indicator for the track to zero in the target data structure for the accessible consistent copy volume.

A computer-implemented method, comprising:

• performing a consistent asynchronous mirror copy that includes an asynchronous mirror copy from a primary volume to a secondary volume and a point-in-time copy from the secondary volume to a tertiary volume;
• receiving an initiation of a point-in-time establish from the secondary volume to an accessible consistent copy volume to start a point-in-time relationship for a point-in-time copy from the secondary volume to the accessible consistent copy volume;
• creating a target data structure for the accessible consistent copy volume with target data structure indicators set to one;
• and
• in response to copying each track from one of the secondary volume and the tertiary volume to the accessible consistent copy volume, updating a target data structure indicator for the track to zero in the target data structure for the accessible consistent copy volume.