Shingled magnetic recording

Shingled magnetic recording (SMR) is a magnetic storage data recording technology used in hard disk drives (HDDs) to increase storage density and overall per-drive storage capacity. Conventional hard disk drives record data by writing non-overlapping concentric magnetic tracks (conventional magnetic recording [CMR], Perpendicular recording), while shingled recording writes new tracks that overlap part of the previously written magnetic track, leaving the previous track narrower and allowing higher track density.

Source: Wikipedia — Shingled magnetic recording (CC BY-SA 4.0)