Storage system with fast recovery and resumption of previously-terminated synchronous replication

A method comprising:

• detecting a condition requiring termination of a synchronous replication mode of a replication process carried out between a first storage system and a second storage system, the first storage system comprising a plurality of storage devices and a storage controller;
• responsive to the detected condition, capturing a snapshot of source data that is subject to replication from the first storage system to the second storage system as part of the replication process;
• terminating the synchronous replication mode of the replication process;
• initiating an asynchronous replication mode of the replication process;
• executing an asynchronous-to-synchronous transition cycle scan operation for the replication process utilizing the captured snapshot;
• and
• resuming the synchronous replication mode of the replication process responsive to successful completion of the asynchronous-to-synchronous transition cycle scan operation;
• wherein the asynchronous-to-synchronous transition cycle scan operation comprises comparing the captured snapshot to another snapshot taken by the first storage system in order to generate differential data for transmission to the second storage system;
• wherein capturing a snapshot of source data that is subject to replication from the first storage system to the second storage system as part of the replication process comprises generating at least one snapshot set for a designated source production consistency group before termination of synchronous replication;
• wherein the first storage system comprises a plurality of storage nodes each comprising one or more of the storage devices and wherein each of the storage nodes of the first storage system further comprises a set of processing modules configured to communicate over one or more networks with corresponding sets of processing modules on other ones of the storage nodes, the sets of processing modules of the storage nodes of the first storage system collectively comprising at least a portion of the storage controller of the first storage system;
• wherein each of the sets of processing modules comprises one or more control modules, one or more routing modules and one or more data modules, and wherein at least one of the sets of processing modules comprises a management module;
• wherein the management module instructs all of the control modules of the storage controller to terminate the synchronous replication mode only after confirmation of suspended generation of replication acknowledgements for host device write requests is received from each of those control modules responsive to respective corresponding instructions from the management module to suspend generation of such replication acknowledgements;
• and
• wherein the method is implemented by at least one processing device comprising a processor coupled to a memory.

A computer program product comprising a non-transitory processor-readable storage medium having stored therein program code of one or more software programs, wherein the program code when executed by at least one processing device of a first storage system comprising a plurality of storage devices and a storage controller causes the first storage system:

• to detect a condition requiring termination of a synchronous replication mode of a replication process carried out between the first storage system and a second storage system;
• responsive to the detected condition, to capture a snapshot of source data that is subject to replication from the first storage system to the second storage system as part of the replication process;
• to terminate the synchronous replication mode of the replication process;
• to initiate an asynchronous replication mode of the replication process;
• to execute an asynchronous-to-synchronous transition cycle scan operation for the replication process utilizing the captured snapshot;
• and
• to resume the synchronous replication mode of the replication process responsive to successful completion of the asynchronous-to-synchronous transition cycle scan operation;
• wherein the asynchronous-to-synchronous transition cycle scan operation comprises comparing the captured snapshot to another snapshot taken by the first storage system in order to generate differential data for transmission to the second storage system;
• wherein capturing a snapshot of source data that is subject to replication from the first storage system to the second storage system as part of the replication process comprises generating at least one snapshot set for a designated source production consistency group before termination of synchronous replication;
• wherein the first storage system comprises a plurality of storage nodes each comprising one or more of the storage devices and wherein each of the storage nodes of the first storage system further comprises a set of processing modules configured to communicate over one or more networks with corresponding sets of processing modules on other ones of the storage nodes, the sets of processing modules of the storage nodes of the first storage system collectively comprising at least a portion of the storage controller of the first storage system;
• wherein each of the sets of processing modules comprises one or more control modules, one or more routing modules and one or more data modules, and wherein at least one of the sets of processing modules comprises a management module;
• and
• wherein the management module instructs all of the control modules of the storage controller to terminate the synchronous replication mode only after confirmation of suspended generation of replication acknowledgements for host device write requests is received from each of those control modules responsive to respective corresponding instructions from the management module to suspend generation of such replication acknowledgements.