Point in time copy operations from source volumes to space efficient target volumes in two stages via a non-volatile storage

A computer program product, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code configured to perform operations on a controller, the operations comprising:

• in response to receiving, by the controller, a request from a host to perform a point in time copy operation from a source volume to a space efficient target volume, performing a first set of operations, the first set of operations comprising:
• updating a bitmap metadata to indicate tracks to be copied for the point in time copy operation, and in response to updating the bitmap metadata sending an indication to the host that the point in time copy operation is complete even though a corresponding physical point in time copy of data stored in the tracks has not committed;
• and
• in response to updating the bitmap metadata, copying, via the controller, by using the bitmap metadata, data stored in the tracks indicated in the bitmap metadata, from the source volume to a non-volatile storage to preserve the point in time copy operation;
• and
• subsequent to completion of the first set of operations, performing a second set of operations, comprising asynchronously copying, via a background process, the data copied in the first set of operations to the non-volatile storage, from the non-volatile storage to the space efficient target volume to perform a commit of the physical point in time copy of the data from the source volume to the space efficient target volume, wherein point in time copy operations are preserved in the non-volatile storage via the first set of operations by copying a group of tracks to a temporary copy in the non-volatile storage, and subsequently in a commit stage that comprises the second set of operations, the temporary copy is copied over asynchronously via the background process to the space efficient target volume to commit the physical point in time copy of the data from the source volume to the space efficient target volume.

A storage controller controlling a source volume and a space efficient target volume, wherein the storage controller is coupled to a host, the storage controller, comprising:

• a non-volatile storage;
• a processor coupled to the non-volatile storage, wherein the processor performs operations, the operations comprising:
• in response to receiving a request from a host to perform a point in time copy operation from the source volume to the space efficient target volume, performing a first set of operations, the first set of operations comprising:
• updating a bitmap metadata to indicate tracks to be copied for the point in time copy operation, and in response to updating the bitmap metadata sending an indication to the host that the point in time copy operation is complete even though a corresponding physical point in time copy of data stored in the tracks has not committed;
• and
• in response to updating the bitmap metadata, copying by using the bitmap metadata, data stored in the tracks indicated in the bitmap metadata, from the source volume to a non-volatile storage to preserve the point in time copy operation;
• and
• subsequent to completion of the first set of operations, performing a second set of operations, comprising asynchronously copying, via a background process, the data copied in the first set of operations to the non-volatile storage, from the non-volatile storage to the space efficient target volume to perform a commit of the physical point in time copy of the data from the source volume to the space efficient target volume, wherein point in time copy operations are preserved in the non-volatile storage via the first set of operations by copying a group of tracks to a temporary copy in the non-volatile storage, and subsequently in a commit stage that comprises the second set of operations, the temporary copy is copied over asynchronously via the background process to the space efficient target volume to commit the physical point in time copy of the data from the source volume to the space efficient target volume.