Cleaning up disk space on Centos OS - web-services

Question

I'm having issues with inconsistently my site going down (giving a 500 error) and when running commands getting:
-jailshell: fork: retry: Resource temporarily unavailable
I'm a noob on the server.
I ran df -h and I got back:
Filesystem Size Used Avail Use% Mounted on
/dev/root 39G 24G 14G 65% /usr/local/cpanel/3rdparty/mailman
/dev/root 152G 102G 49G 68% /var/spool
/dev/root 39G 24G 14G 65% /usr/sbin
/dev/root 15G 9.3G 4.3G 69% /etc/mail
/dev/root 9.5G 1.3G 7.8G 15% /var/tmp
/dev/root 15G 9.3G 4.3G 69% /lib64
/dev/root 15G 9.3G 4.3G 69% /sbin
/dev/root 15G 9.3G 4.3G 69% /opt
/dev/root 39G 24G 14G 65% /usr
/dev/root 152G 102G 49G 68% /var
/dev/root 9.5G 1.3G 7.8G 15% /tmp
/dev/root 32G 164K 32G 1% /dev
/dev/root 15G 9.3G 4.3G 69% /bin
/dev/root 15G 9.3G 4.3G 69% /lib
/dev/root 1.8T 1.2T 639G 65% /home4/sitedir
sitedir being where everything is hosted.
I feel that 1.2T of mem being used is a lot. But i'm unsure. Is there anyway I can look at what's causing this amount of memory in /home4/sitedir and possibly how I could clean it up?

Answer 1

For starters, try running the top command as root and press the m key to sort the processes by memory once top is running. You should see the processes using the most memory since the m key sorts by memory usage.
As I mentioned in my comment above, the question asks about disk space but then refers to memory in the body. You have a command to give you the disk space ( df -h ) so I am giving you a response for the (possible) memory side of the your question, if indeed that is what you are concerned about.