Create a checkpoint for a set of data units

摘要

A memory module stores working data that includes data units. A storage system stores recovery data that includes sets of one or more data units. Transferring data units between the memory module and the storage system includes: maintaining an order among the data units included in the working data, the order defining a first contiguous portion and a second contiguous portion; and, for each of multiple time intervals, identifying any data units accessed from the working data during the time interval, and adding to the recovery data a set of two or more data units including: one or more data units from the first contiguous portion including any accessed data units, and one or more data units from the second contiguous portion including at least one data unit that has been previously added to the recovery data.