What CloudLinux does.
In traditional shared hosting, one site on the server can bring the entire server to its knees, by taking up all the server's resources. This leaves the remaining web sites with no server resources (CPU, entry processes and memory) and all sites on the server become unreachable.
CloudLinux prevents this from happening by isolating each site in its own silo with a maximum allocation of resources (CPU, entry processes and memory) This is done with Light Visualised Environment (LVE) technology, a fancy term for isolating cPanel domains so they don't crash your server due to run away scripts, WordPress attacks and other causes of high resource usage.
LVE is an isolation technology that limits and controls the amount of resources (CPU, entry processes and memory) available to a specific process or user. This allows for greater stability and enhanced reliability but the downside is that the affected users website will show an error when it hits the limit on the amount of system resources. Email is not affected.
Resource Limits
The default isolation limits we set are 1GB memory, 1 CPU and 20 Entry Processes. These limits are more then enough for an average site with 70 - 100 concurrent users. Busier websites will need these limits raised.
Entry Processes refer to how many PHP scripts are running on the site at the one time. It is not the number of visitors on the site, in fact 20 processes can usually handle the same 70-100 concurrent visitors. The processes typically only last a fraction of a second so if a site is reaching this limit it will indicate a problem with the scripting
When a site reaches one or more of the limits it will display a 500 error page
If a site is legitimately reaching the limits they can be adjusted on a per site basis. For Managed Servers please submit a ticket and we can make the adjustment for you. If your server is unmanaged you can use the documentation below
Documentation
You can learn more about CloudLinux here and instructions on how to adjust the limits here
