Auxilary LRU list to improve asynchronous data replication performance

A computer program product for improving asynchronous data replication between a primary storage system and a secondary storage system, the computer program product comprising a non-transitory computer-readable storage medium having computer-usable program code embodied therein, the computer-usable program code configured to perform the following when executed by at least one processor:

• monitor, in a cache of the primary storage system, unmirrored data elements needing to be mirrored, but that have not yet been mirrored, from the primary storage system to the secondary storage system;
• maintain a regular LRU (least recently used) list designating an order in which data elements, including the unmirrored data elements, are demoted from the cache, the regular LRU list comprising an LRU end and an MRU (most recently used) end;
• determine whether a data element referenced at the LRU end of the regular LRU list is an unmirrored data element;
• and
• in the event the data element referenced at the LRU end of the regular LRU list is an unmirrored data element, move a reference to the data element to a transfer-pending LRU list dedicated to unmirrored data elements in the cache, and moving the data element from a higher performance portion of the cache to a lower performance portion of the cache.

A system for improving asynchronous data replication between a primary storage system and a secondary storage system, the system comprising:

• at least one processor;
• at least one memory device operably coupled to the at least one processor and storing instructions for execution on the at least one processor, the instructions causing the at least one processor to:
• monitor, in a cache of the primary storage system, unmirrored data elements needing to be mirrored, but that have not yet been mirrored, from the primary storage system to the secondary storage system;
• maintain a regular LRU (least recently used) list designating an order in which data elements, including the unmirrored data elements, are demoted from the cache, the regular LRU list comprising an LRU end and an MRU (most recently used) end;
• determine whether a data element referenced at the LRU end of the regular LRU list is an unmirrored data element;
• and
• in the event the data element referenced at the LRU end of the regular LRU list is an unmirrored data element, move a reference to the data element to a transfer-pending LRU list dedicated to unmirrored data elements in the cache, and moving the data element from a higher performance portion of the cache to a lower performance portion of the cache.