As we all know, Solid State Drives (SSD) are expensive ($/Gb) but they are quick to access. I'm wondering if there exists a sort of software-kernel-level 'cache swap' filesystem technology; the idea of such filesystem is that it keeps a cache of frequently accessed files on the main HDD, so;
- you get the benefits of SSD speed access for 90% of circumstances
- you get the benefits of cheap long-term storage for files that have not been used in a while