Whether you are the administrator for your own server and hosting multiple virtual private servers (VPS) or you are a VPS user sharing a server with others, the question of security is definitely one you might want to ask. How secure are virtual private servers? Does each VPS administrator potentially pose a security risk to the others?
One of the benefits of a VPS and virtualization in general is that you can run a complete and functional installation of an operating system within another OS installation. For example, you can run a fully-functional Windows installation from within Linux. Furthermore, unlike emulation, virtual machines tap directly into the hardware, requiring no extra CPU power.
Moreover, a VPS is installed in something called a container. In Linux, there is the concept of a chroot jail, within which is a complete installation of an operating system. For the user, the VPS appears to function exactly like a dedicated server, providing full root access and all of the administrative privileges that accompany that access. In reality, however, that user cannot navigate outside of his container and is always restricted within it.
Even if the OS within a virtual machine crashes, freezes, or is otherwise disrupted, the rest of the server and the other VPS containers will continue to function normally. Furthermore, each container is only allocated a specified amount of CPU power and memory. Even if that is maxed out by some anomaly, the rest of the server should continue to function as expected. Therefore, virtual private servers are very secure for you as a dedicated server system administrator and for other VPS users.