I have a question about how CloudLinux consumes system memory. I've read through all of the comments about memory and most are related to LVEs. Nothing about this issue:
I have a server with a moderate number of high traffic websites that was hosted on a server with 4GB RAM and a 4-core processor. I needed faster i/o so I migrated to an 8GB server with a faster 4-core processor and fast disks.
Everything runs fine - the server handles the sites & traffic well. I thought this would be a good server to test CloudLinux. After installing CloudLinux, server memory use jumped from +/- 2GB to over 6GB. It seems as if every time I create a new vhost, memory use goes up by about 100MB.
Can you verify that each new LVE consumes 100GB RAM? I don't intend to put 100's of sites on this server but it seems that CloudLinux severely restricts the number of sites I can add to the server. Unless I am completely misunderstanding LVE configuration, which is possible.
Linux has disk caching enabled always -- you cannot disable it. I think you should read this: http://www.linuxatemyram.com/
It really sounds like you are mixing up disk caching with RAM being unavailable.