We use the Cloudlinux operating system on our shared hosting site. Its main difference from the usual system, that it allows to allocate to each user a guaranteed amount of resources (memory and CPU), which can not be exceeded. On most virtual hosting system works differently, all the resources of the system are divided among all the users as a result very often there are situations where one user takes over all the resources of the server and the other client sites on the same server begin to slow.
We exclude such a situation, one site can not “put” the entire server and can not affect the work of other sites. If one site reaches its allotted limits, its requests begin to be processed at a lower priority, and the site does not stop working, but simply works slower, but on the other sites it has no effect.
At different rates we allocate different amount of CPU and memory resources, all rates are chosen so that they are enough for most sites.