1. A computer program product comprising a computer storage medium having program instructions that when executed manage spare space in a storage device by performing operations, the operations, comprising: determining a current write amplification based on storage writes to a media at the storage device and host writes from a host to the storage device; determining an adjustment to the current write amplification to produce an adjusted write amplification based on an estimated lifespan of the storage device, a maximum storage writes for the storage device, and the storage writes at the storage device since the storage device was powered-on; determining an adjustment to the spare space based on the adjusted write amplification, wherein the spare space comprises overprovisioned storage space not comprising user accessible storage; and initiating an operation to reconfigure the spare space and the free space available to the user to adjust the spare space by the determined adjustment to the spare space.