I'm looking for some kind of cache functionality for specific directory in Linux as I've got a few applications that use this directory frequently and very often.
I use HDD (not SSD) and I'm wondering if it is possible to put some cache functionality on top of ext4 directory to reduce number of these HDD accesses? I'm thinking about something which could caches these read/writes to this directory and from time to time (let's say once per 30seconds) sync them with directory on physical HDD.
I know about overlayfs and tmpfs but they need some external copyings the files from them to physical HDD.
Any other ideas how to approach this?
