Defrag tools are on the verge of extinction.
SSD drives are making them superfluous when not plain disruptive.
But SSD sizes are not catching up anytime soon with conventional HDs. Multimedia files are filling up gigabytes of space and their placement on solid state drives is too expensive, while benefits are minimal for occasional access.
What is really needed is a hierarchical file system that can handle multiple drives at once.
A big mechanical HD would be paired with an SSD drive.
Frequently accessed sectors would be replicated on the SSD for faster access. All writes should be directed on the SSD for faster I/O completion. Files would then be written back to the HD in the background while optimizing placement and seeks of the magnetic head.
Hybrid disks like the Seagate Momentus seems to be moving that way, but a really small cache limits its benefit.
A software solution at the file system level can be more flexible by allowing mixing different sizes of SSD and HD, and a higher level of abstraction may allow better optimization than a simple cache.
After virtualization, is this another Mainframe technology going from datacenters to homes?