I am currently running concrete5 and mysql installed on two identical Windows/Apache servers. When I approach 4500 concurrent users across these two boxes my CPU hits 100% and pretty much locks up.
I am in the process of moving my concrete5 installation from Windows/Apache servers to CentOS/Apache installation and upgrading concrete5.

I have 3 apache servers pointing to one NFS mounted directory for the content, excluding /config/site.php and the cache directory. These 3 server sit behind redundant load balancers.

I excluded /site.php so I can designate a fourth server for dashboard access without impacting the other three servers and so I can make it available outside of the load balancer.

I am not using sticky sessions through the loadbalancer, just round-robin. I do not see the need to persist sessions for static non-session site, unless I am wrong.

The problem I am having is that when I access the dashboard through the separate dashboard instance, it doesn't seem to hold, the dashboard disappears and sometimes concrete5 is crashing. I have /site.php pointing to this site's specific domain name.

Has anyone done something like this or am I off base?