Stefan Mileschin

It's not just planar NAND that's running into physical limits lately. According to Seagate, its latest 1TB platter 3.5" drives have shrunk read/write heads as small as they can physically go. Similarly, tracks on those platters are placed as close together as physically possible. Pushing areal density is important to increase overall capacities (no one wants to see more platters per drive), but if we're at physical limits today then it's time for some architectural changes to push capacities going forward.

Seagate's solution is something it calls Shingled Magneting Recording (SMR). The process is pretty simple. Track size is traditionally defined by the size of the write heads, as they are larger than the read heads. The track width is larger than necessary from the perspective of reading data back in order to decrease the chances of reading data from adjacent tracks. Seagate's SMR exploits this reality.

http://www.anandtech.com/show/7290/s...etic-recording