1. A method comprising: receiving a write request from a storage controller to write data from a main data store to a data storage cache, the data storage cache divided into an advertised space portion and an over-provisioned space portion, wherein clusters marked as pending eviction correspond to the over-provisioned space portion and clusters not marked as pending eviction correspond to the advertised space portion; and marking one or more clusters of data on the data storage cache as pending eviction if the data storage cache satisfies a saturation condition.