Data storage system employing a hot spare to store and service accesses to data having lower associated wear

A controller monitors access frequencies of address ranges mapped to a data storage array. Based on the monitoring, the controller identifies frequently accessed ones of the address ranges that have lower associated wear, for example, those that are read more often than written. In response to the identifying, the controller initiates copying of a dataset associated with the identified address ranges from the data storage array to a spare storage device while refraining from copying other data from the data storage array onto the spare storage device. The controller directs read input/output operations (IOPs) targeting the identified address ranges to be serviced by access to the spare storage device. In response to a failure of a failed storage device among the plurality of primary storage devices, the controller rebuilds contents of the failed storage device on the spare storage device in place of the dataset associated with the identified address ranges.