A data preservation subsystem in a computing system, the data preservation subsystem comprising: a battery-backed memory having an aperture, the aperture having a flush order which is an order of copying data from the aperture to an aperture-associated non-volatile storage in response to a data integrity threat, the flush order defining a first-to-flush end of the aperture and a last-to-flush end of the aperture; a data preservation circuitry in operable communication with the battery-backed memory, the data preservation circuitry configured to perform data preservation steps that include (a) receiving a request to store a dataset A-data in the aperture, A-data including data which is designated as critical data, (b) identifying a portion A-memory of unallocated memory of the aperture, A-memory being large enough to hold A-data, A-memory having an address which is closer to the aperture first-to-flush end than any other address of any other unallocated memory of the aperture, (c) marking A-memory as allocated and placing a copy of A-data in A-memory, (d) receiving a request to store a dataset Z-data in the aperture, Z-data not including any data which is designated as critical data, (e) identifying a portion Z-memory of unallocated memory of the aperture, Z-memory being large enough to hold Z-data, Z-memory having an address which is closer to the aperture last-to-flush end than any other address of any other unallocated memory of the aperture, (f) marking Z-memory as allocated and placing a copy of Z-data in Z-memory; wherein the data preservation subsystem is configured to provide a higher likelihood of successfully flushing critical data and thereby preserving it than by storing data in the battery-backed memory without regard to data criticality a battery-backed memory having an aperture, the aperture having a flush order which is an order of copying data from the aperture to an aperture-associated non-volatile storage in response to a data integrity threat, the flush order defining a first-to-flush end of the aperture and a last-to-flush end of the aperture; a data preservation circuitry in operable communication with the battery-backed memory, the data preservation circuitry configured to perform data preservation steps that include (a) receiving a request to store a dataset A-data in the aperture, A-data including data which is designated as critical data, (b) identifying a portion A-memory of unallocated memory of the aperture, A-memory being large enough to hold A-data, A-memory having an address which is closer to the aperture first-to-flush end than any other address of any other unallocated memory of the aperture, (c) marking A-memory as allocated and placing a copy of A-data in A-memory, (d) receiving a request to store a dataset Z-data in the aperture, Z-data not including any data which is designated as critical data, (e) identifying a portion Z-memory of unallocated memory of the aperture, Z-memory being large enough to hold Z-data, Z-memory having an address which is closer to the aperture last-to-flush end than any other address of any other unallocated memory of the aperture, (f) marking Z-memory as allocated and placing a copy of Z-data in Z-memory; wherein the data preservation subsystem is configured to provide a higher likelihood of successfully flushing critical data and thereby preserving it than by storing data in the battery-backed memory without regard to data criticality