The present invention is directed to systems and methods for optimizing garbage collection in data storage. The data storage may be a shingled disk drive or a non-volatile solid-state memory device. Garbage collection is optimized by selectively saving data read from certain locations of the data storage in response to host read commands and using the saved data for subsequent garbage collection operations. The decision of whether to save data may be based on a number of criteria, including whether the data is located in an area of the data storage that is due to be garbage collected in the near future. In this manner, certain garbage collection operations can be performed without having to re-read the saved data.