Methods, systems, and computer program products for performing an input/output (I/O) operation that includes a virtual drain

A system for performing an input/output (I/O) operation that includes a virtual drain, the system comprising:

• (a) a write processor for:
• (i) receiving and accepting write requests to a source storage entity for which a request for an I/O operation involving the copying of data from the source storage entity to a destination storage entity has been received;
• (ii) associating each accepted write request with context information that describes the context in which the write request was accepted, wherein the context information comprises at least one a status of the source storage entity at the time that the write request was accepted and a configuration of the source storage entity at the time that the write request was accepted;
• and
• (b) a queue processor for:
• (i) determining, maintaining, and indicating the status of received write requests;
• (ii) arresting write requests to the source storage entity for which the request for performing the I/O operation involving copying of data from the source storage entity to the destination storage entity has been received by preventing write requests from being placed into a write queue for storing write requests to the source storage entity;
• and
• (iii) performing a virtual drain, wherein performing the virtual drain includes identifying, and indicating as deferred, pending writes to the source storage entity, and for indicating that the virtual drain is complete, wherein a pending write is a write request that exists in the write queue and has not yet been processed and wherein a deferred write comprises a write request which is processed after performing the I/O operation and which is processed in the context in which the deferred write was accepted, and wherein, after the virtual drain is indicated as being complete, the write processor performs the I/O operation;
• wherein, after the I/O operation is performed, the queue processor releases write requests to the source storage entity by allowing write requests to be placed into the write queue and the write processor processes the deferred write requests using the context information.

A computer program product comprising computer executable instructions embodied in a computer readable medium for performing a virtual drain, the steps comprising:

• (a) receiving a request to perform an input/output (I/O) operation involving copying of data from a source storage entity to a destination storage entity;
• and
• (b) in response to receiving the I/O request:
• (i) arresting write requests to the source storage entity by preventing write requests from being placed into a write queue for storing write requests to the source storage entity;
• (ii) performing a virtual drain, wherein performing a virtual drain includes identifying, and indicating as deferred, pending writes to the source storage entity, wherein a pending write is a write request that exists in the write queue and has not yet been processed and wherein a deferred write comprises a write request which is processed after performing the I/O operation and which is processed in the context in which the deferred write was accepted;
• (iii) performing the I/O operation, and after performing the I/O operation:
• (a) releasing write requests to the source storage entity by allowing write requests to be placed into the write queue;
• and
• (b) processing each deferred write request using context information that is associated with the deferred write request and that describes the context in which the deferred write request was accepted, wherein the context information comprises at least one of a status of the source storage entity at the time that the deferred write request was accepted and a configuration of the source storage entity at the time that the deferred write request was accepted.