With up to 85 percent of data in an enterprise system being infrequently accessed, cost-efficiency can be substantially increased by maintaining frequently accessed data (aka hot data) in-memory while moving less frequently accessed data (aka warm data) to persistent, external storage.
For SAP S4/HANA applications, this approach is enabled by the Native Storage Extension (NSE) feature in SAP HANA.
Recent testing of IBM FlashSystem 9200 in combination with SAP HANA NSE demonstrates that organizations can safely replace 25%
of more costly RAM capacity with much less expensive IBM FlashSystem storage, without impacting performance when enabling the NSE feature as recommended by the SAP HANA advisor tool.
Here's a very rough architecture overview of a SAP HANA environment with NSE enabled: