I run a forum for a small community, running Invision 3.4.7. (We can't update to 4 just yet, but will eventually). We've got a few hundred active members. Roughly only 15-40 members online at a time most of the time. On special occasions up to 100. Our database is pretty big: 2.8 gb (1.4 million posts, 9,000 total members).

Our server is a VPS. Ram: "up to" 8gb (guaranteed 4gb). 200 gb space (we only use about 9). Linux w/Centos 6 and Plesk 12. Apache/Mysql/PHP. We've been on this one for about 2 years.

When the site is busy, the board loads extremely slowly. It doesn't take much. Maybe 40 or more members actively posting and refreshing topics. 

Note: Parallels Power Panel logs a resource alert for dcachesize a few times an hour. (soft limit is 25 mb, hard limit is 30 mb)

 What I'm wondering is: Should I be focusing on finding a better/faster server or on diagnosing a problem with the site or server configuration?  

I know it's probably difficult to judge without further information, but generally... is this pretty clearly not an adequate server for the size of our site? i.e. I might as well move to a new one with up-to-date everything and more generous limits.

Or should a site this size run fine on this configuration? i.e. I should stay, upgrade system software and search for problems or ways to optimize?

 

Thanks for any advice you can give!

 

 

Would help more if you explained a bit about your config, php/sql versions, any opcache etc.

Really hard to say without detailed Informations, but normally, you should be fine wirh 4GB on Centos6.
Which databaseserver do you use (MySQL Version? MariaDB ? )

BTW: i really recommend to upgrade to Centos 7.x and Plesk Onyx (Version 17)

Thank you. Yes, I know we really need to upgrade a few things. Wondering if its worth the trouble to do it now or start on a new server.

PHP:  5.3.3    Mysql:  5.1.73   

(Not familiar with opcache. Searched online and sounds like it started with PHP 5.5, so I'll say we don't have that) 

 

It's time to get some updates :-)

Ipb 4

Nginx

Phpfpm 7.0.x

MariaDB

Zend opcache

Memcached

Convert database tables to Innodb 

and with a few system optimizations you will see a huge performance difference :-)