Clarified Question:
When the OS sends the command to write a sector to disk is it atomic? i.e. Write of new data succeeds fully or old data is left intact should the power fail immediately followin...

According to Btrfs developer Chris Mason, tuning Linux filesystems to work
well on solid-state storage devices is a lot like working on an old,
clunky car.  Lots of work goes into just trying to make the thing run with
decent performance.  Old cars may have mainly hardware-related problems,
but, with Linux,
the bottleneck is almost always to be found in the software.  It is, he
said, hard to give a customer a high-performance device and expect them to
actually see that performance in their application.  Fixing this problem
will require work in a lot of areas.  One of those areas, supporting and
using atomic I/O operations, shows particular potential.