Queue management in multi-site storage systems

1. A computer-implemented method comprising:

receiving, from a host, by a backup storage system, a request to process a first set of Input/Output (I/O) queues on the backup storage system, wherein the backup storage system is a second subsystem in a multi-site storage system;

allocating memory on the backup storage system for processing the first set of I/O queues;

identifying a second set of I/O queues established at a primary storage system, wherein the primary storage system is a first subsystem in the multi-site storage system and the backup storage system includes a backup copy of data stored on the primary storage system;

determining the first set of I/O queues are redundant, wherein the first set of I/O queues are redundant when the first set of I/O queues and the second set of I/O queues process an equivalent set of commands, as included in the request;

responsive to determining that the first set of I/O queues are redundant:

notifying via the host, that the first set of I/O queues are redundant;

terminating a connection between the host and the backup storage system; and

de-allocating the memory to process the first set of I/O queues.

2. The method of claim 1 further comprising:

monitoring processing of the second set of I/O queues;

determining a failure of the primary storage system;

notifying the host of the failure of the primary storage system;

in response to determining the failure of the primary storage system, re-establishing the connection between the host and the backup storage system and re-allocating the memory to the second set of I/O queues on the backup storage system; and

processing the second set of I/O queues on the backup storage system.

3. The method of claim 1 , wherein the host, the primary storage system, and the backup storage system use a non-volatile memory express (NVMe) protocol.

4. The method of claim 3 , wherein the notifying occurs via an asynchronous event request through an NVMe qualified name (NQN) connection.

5. The method of claim 1 , further comprising:

receiving, from the host, a second request to process the first set of I/O queues;

determining the request includes an override flag;

processing, in response to the determining that the request includes the override flag, the first set of I/O queues on the backup storage system.

6. The method of claim 1 , wherein the notifying occurs via an out-of-band communications.

7. The method of claim 6 , wherein the out of band communication includes an application programming interface call.

8. The method of claim 1 , wherein the primary storage system and the backup storage system are included in a disaster recovery system.

9. The method of claim 8 , wherein the disaster recovery system syncs data between the primary storage system and the backup storage system.

10. A system comprising:

a processor; and

a computer-readable storage medium communicatively coupled to the processor and storing program instructions which, when executed by the processor, are configured to cause the processor to:

receive, from a host, by a backup storage system, a request to process a first set of Input/Output (I/O) queues on the backup storage system, wherein the backup storage system is a second subsystem in a multi-site storage system;

allocate memory on the backup storage system for processing the first set of I/O queues;

identify a second set of I/O queues established at a primary storage system, wherein the primary storage system is a first subsystem in the multi-site storage system and the backup storage system includes a backup copy of data stored on the primary storage system;

determine the first set of I/O queues are redundant, wherein the first set of I/O queues are redundant when the first set of I/O queues and the second set of I/O queues process an equivalent set of commands, as included in the request;

responsive to determining that the first set of I/O queues are redundant:

notify via the host, that the first set of I/O queues are redundant;

terminate a connection between the host and the backup storage system; and

de-allocate the memory to process the first set of I/O queues.

11. The system of claim 10 , wherein the program instructions are further configured to cause the processor to:

monitor processing of the second set of I/O queues;

determine, a failure of the primary storage system;

notify the host of the failure of the primary storage system;

re-establish, in response to determining the failure of the primary storage system, the connection between the host and the backup storage system and re-allocate the memory to the second set of I/O queues on the backup storage system; and

process the second set of I/O queues on the backup storage system.

12. The system of claim 10 , wherein the host, the primary storage system, and the backup storage system use a non-volatile memory express (NVMe) protocol.

13. The system of claim 10 , wherein the program instructions are further configured to cause the processor to:

receive, from the host, a second request to process the first set of I/O queues;

determine, the request includes an override flag;

process, in response to determining the request includes the override flag, the first set of I/O queues on the backup storage system.

14. A computer program product, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processing unit to cause the processing unit to:

receive, from a host, by a backup storage system, a request to process a first set of Input/Output (I/O) queues on the backup storage system, wherein the backup storage system is a second subsystem in a multi-site storage system;

allocate memory on the backup storage system for processing the first set of I/O queues;

identify a second set of I/O queues established at a primary storage system, wherein the primary storage system is a first subsystem in the multi-site storage system and the backup storage system includes a backup copy of data stored on the primary storage system;

determine the first set of I/O queues are redundant, wherein the first set of I/O queues are redundant when the first set of I/O queues and the second set of I/O queues process an equivalent set of commands, as included in the request;

responsive to determining that the first set of I/O queues are redundant:

notify via the host, that the first set of I/O queues are redundant;

terminate a connection between the host and the backup storage system; and

de-allocate the memory to process the first set of I/O queues.

15. The computer program product of claim 14 , wherein the program instructions are further configured to cause the processing unit to:

monitor processing of the second set of I/O queues;

determine, a failure of the primary storage system;

notify the host of the failure of the primary storage system;

re-establish, in response to determining the failure of the primary storage system, the connection between the host and the backup storage system and re-allocate the memory to the second set of I/O queues on the backup storage system; and

process the second set of I/O queues on the backup storage system.

16. The computer program product of claim 14 , wherein the host, the primary storage system, and the backup storage system use a non-volatile memory express (NVMe) protocol.

17. The computer program product of claim 14 , wherein the program instructions are further configured to cause the processing unit to:

receive, from the host, a second request to process the first set of I/O queues;

determine, the request includes an override flag;

process, in response to determining the request includes the override flag, the first set of I/O queues on the backup storage system.