On Sat, Sep 06, 2014 at 05:46:58PM +0100, James Wade wrote: I generally recommend against installing any sort of "panel" software like CPanel, because they replace standard system binaries and configurations leading you into a situation where you only know how to administer the panel software, not a Linux system. I've never heard of ZPanel and have no idea if it's anything like CPanel; I hope not. Can we see the current header from "top" please? Can we see the output of: ps -C apache2 -FH (may have to do "-C httpd" if apache binary is called httpd on CentOS; I forget) Finally this one will give us all processes sorted by how much memory they are using: ps -eo pmem,pcpu,vsize,pid,cmd | sort -k 1 -nr For a quick look, put a "head" on the end: ps -eo pmem,pcpu,vsize,pid,cmd | sort -k 1 -nr | head The typical strategy here will be: 1. Disable any apache2 modules that you don't need and restart apache2. 2. See how big a single apache2 worker process is. Call that A. 3. See about how much memory you have left. Call that F. 3. F divided by A is how many apache2 workers you can have running at once without the server going into swap. Make sure that MaxClients and StartServers are <= that number. For example, if you have about 120M of spare memory and each Apache child is using about 24M of virtual memory then try setting MaxClients to 5, StartServers to 2 and MinSpareServers to 1. In Debian these settings would be found in /etc/apache2/apache2.conf. If you had mistakenly set MaxClients to say, 20, then 20x24=480M so host goes into swap, every grinds to a halt. By restricting the number of apache2 workers you just make web serving slow. Which is still not great, but is better than everything being unusable. For greater performance, switch to something like lighttpd or Nginx with PHP as a pool of FastCGI processes. Cheers, Andy -- http://bitfolk.com/ -- No-nonsense VPS hosting

Andy said: I use suphp, which means that my Apache process is quite small (it's not loading PHP for things that do not need it). The active modules are alias, auth_basic, authn_file, authz_default, authz_host, authz_user, autoindex, cgi, deflate, dir, mime, rewrite, ssl, suphp. If I didn't use Apache's authorisation for access for wp-login.php (it's another defence against the bots trying to bruteforce access to any WordPress site), I could lose a couple of the auth modules. Similarly, if I weren't using SSL for some sites' admin pages, I could lose ssl. Ian