Linux ate ram as disk cache

One day QA asked why memory was really low in QA linux server. Really not sure, this question is interesting for me, as known, our java applications always configured memory limitation, shouldn't happen low memory issue.

From result of "free -m" command executed and checked, If you just naively look at "used" and "free", you'll think your ram is 98/99% full.

Googling that situation, linuxatemyram, what's going on?
Linux is borrowing unused memory for disk caching. This makes it looks like you are low on memory, but everything is fine. Try to use unused memory as disk caching makes the system much faster and more responsive.

If you deeply read "linux ate ram", don't panic, your ram is fine. ^^!