Seagate has begun shipping hard drives based on a new technology
dubbed Shingled Magnetic Recording. SMR, as it's called, preserves the
perpendicular bit orientation of current HDDs but changes the way that
tracks are organized. Instead of laying out the tracks individually, SMR stacks them on top of each other
in a staggered fashion that resembles the shingles on a roof. Although
this overlap enables higher bit densities, it comes with a penalty.
Rewrites compromise the data on the following track, which must be read
and rewritten, which in turn compromises the data on the following
track, and so on. SMR distributes the layered tracks in narrow bands to
mitigate the performance penalty associated with rewrites. The makeup
of those bands will vary based on the drive's intended application. We
should see the first examples of SMR next year, when Seagate intends to introduce a 5TB drive with 1.25TB per platter. Traditional hard drives top out at 4TB and 1TB per platter right now.
