...When I've written cache system, I've always used the file system directly. The only catch is that some operating systems limit the number of files on disk or in a directory; a very active server could hit those limits using individual files....
And on certain filesystems, lookups from filenames to files can be slow if there are many files in the same directory.
If we go for direct filesystem storage (which I think should be perfectly ok to implement a Store), I think we need a clever mapping scheme to avoid having more than N files in the same directory.
-Bertrand
