The Debian 8 file server is always full of RAM. What can be done?

Question

linux

Good afternoon!
On a Debian 8 server, RAM is always full.

%Cpu(s):  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:    524288 total,  524288 used,        0 free,        0 buffers
KiB Swap:        0 total,        0 used,        0 free.    27192 cached Mem

free -m 
                 total      used      free    shared    buffers    cached
Mem:          512        512          0        439          0        26
-/+ buffers/cache:        485        26
Swap:            0          0          0

Of the services, only Apache and MySQL work.
Please advise how this issue can be resolved.

Answer 1

increase RAM

Answer 2

Well, 512 MB is not enough, as it were, for everything, so add it. As an option, look:
ps aux --sort=-%mem
Filter out processes that ate memory, and then see who they belong to and how you can optimize them.

Answer 3

del
Inattentively looked.

Answer 4

Of the services, only Apache and MySQL work.
Please advise how this issue can be resolved.

To limit the use of memory by these services (especially the DBMS), obviously. On the other hand, at 512 meters, the muscle will not pull anything more or less loaded.