I have a Ruby on Rails application that stores it's catched files on the filesystem (Rails file-system cache). I was thinking about changing to memcached Store, but a short test shows it isn't a big difference in speed. From linuxatemyram.com I learned a bit about file caching. On the current machine there would be around 40..45GB RAM left which isn't needed for the application and which can be used to linux-disk-cache this rails file cache store. The disk is a RAID10 system with almost 120MB disk perfomance. How can I tell Linux to use free RAM more deliberately and not to be shy about using it? Do think it's necessary to adjust a sysyctl/.. value here, or would I have performance advantages to put the File Store root diretory on a ramdisk? (Loosing the cache during a reboot wouldn't be a problem)