Switching over from using a first primary storage to using a second primary storage when the first primary storage is in a mirror relationship

A computer program product for switching between a first primary storage and a secondary primary storage in communication with a secondary storage, wherein the computer program product comprises a computer readable storage medium having program instructions that when executed by a processor perform operations, the operations comprising:

• migrating data in the first primary storage to the second primary storage while the data in the first primary storage indicated in first change recording information is mirrored to the secondary storage, wherein the first change recording information indicates data from the first primary storage to mirror to the secondary storage;
• after completing the migrating of data from the first primary storage to the second primary storage, indicating writes received to the first primary storage in the first change recording information;
• switching from using the first primary storage to the second primary storage for host read and write access after completing the migrating of data from the first primary storage to the second primary storage;
• after switching to using the second primary storage, indicating changes to the second primary storage in second change recording information indicating data from the second primary storage to mirror to the secondary storage;
• and
• copying writes from the second primary storage indicated in the first and the second change recording information to the secondary storage.

A system for switching between a first primary storage and a second primary storage and further in communication with a secondary storage, comprising:

• a processor;
• and
• a computer readable storage medium having program instructions embodied therewith that when executed by the processor cause operations, the operations comprising:
• migrating data in the first primary storage to the second primary storage while the data in the first primary storage indicated in first change recording information is mirrored to the secondary storage, wherein the first change recording information indicates data from the first primary storage to mirror to the secondary storage;
• after completing the migrating of data from the first primary storage to the second primary storage, indicating writes received to the first primary storage in the first change recording information;
• switching from using the first primary storage to the second primary storage for host read and write access after completing the migrating of data from the first primary storage to the second primary storage;
• after switching to using the second primary storage, indicating changes to the second primary storage in second change recording information indicating data from the second primary storage to mirror to the secondary storage;
• and
• copying writes from the second primary storage indicated in the first and the second change recording information to the secondary storage.

A method for switching between a first primary storage, and a second primary storage, comprising:

• migrating data in the first primary storage to the second primary storage while the data in the first primary storage indicated in first change recording information is mirrored to the secondary storage, wherein the first change recording information indicates data from the first primary storage to mirror to the secondary storage;
• after completing the migrating of data from the first primary storage to the second primary storage, indicating writes received to the first primary storage in the first change recording information;
• switching from using the first primary storage to the second primary storage for host read and write access after completing the migrating of data from the first primary storage to the second primary storage;
• after switching to using the second primary storage, indicating changes to the second primary storage in second change recording information indicating data from the second primary storage to mirror to the secondary storage;
• and
• copying writes from the second primary storage indicated in the first and the second change recording information to the secondary storage.