Detecting data loss during site switchover

A computer system for storing and retrieving data from a plurality of storage volumes, computer system comprising:

• a memory;
• and
• a processor coupled to the memory to read instructions therefrom and perform the following actions by executing the instructions:
• write to non-volatile memory of a first node a plurality of operations of a second node, wherein the first and second nodes are distributed geographically;
• receive an indication of a first number of operations yet to be completed by the second node after failure of the second node;
• determine whether at least one operation is missing from the plurality of operations by calculating whether the first number of operations is larger than the second number of operations;
• and
• in response to the determination that at least one operation is missing, making a volume, of the plurality of storage volumes, unavailable for Input/Output (I/O) operations.

A computer-readable medium having instructions recorded thereon, that when executed by a processor, cause the processor to perform operations, comprising:

• storing at a first node a plurality of operations of a second node, the first and second nodes being mirrored partners;
• during a switchover from the second node to the first node, receiving an indication of a first number of operations yet to be completed by the second node, wherein the switchover includes transferring ownership of a storage volume from the second node to the first node;
• comparing the first number of operations yet to be completed to a second number of operations in the plurality of operations first node;
• in response to the comparing, determining whether at least one operation is missing from the plurality of operations;
• and
• in response to determining that at least one operation is missing, failing the storage volume.