What is a VPS (Virtual Private Server)

Many types of Virtualization technologies exist in the market today and all of the these technologies take a slightly different approach to the same end result, which is a large physical server sliced up into a number of smaller "Virtual Servers". Web24 provides four different virtualization technologies to customers as each have their own purpose and excel in different application.

Simplistically stated (ignoring paravirtualization, emulation and full virtualization) we can group virtualization into two categories.

Operating System Level Virtualization

• Virtuozzo (Windows and Linux VPS)

Hypervisor Based Virtualization

• Xen (Linux VDS)
• Hyper-V (Windows VDS)
• VMWare (Enterprise VDS)

When we use the term Virtual Private Server (VPS) we are referring to a type of Virtualization known as "Operating System Level Virtualization". When we use the term "Virtual Dedicated Server (VDS) we are referring to Hypervisor based virtualization.

Some examples of OS Level Virtualization are

• Virtuozzo (Commercial Version OS Level Virtualization)
• OpenVZ (Open Source Virtuozzo)
• Solaris Containers
• FreeBSD Jails
• Linux VServers

So what is "Operating System Level Virtualization"?

OS Level Virtualization is a way of creating very efficient "containers" or "virtual environments" by utilizing a single base operating system with strong resource sharing and isolation for the guest containers. VPS's look and feel just like a separate machine with its own file systems, IP addresses and software configurations. Because there are no overheads for tasks such as virtualizing CPU's and virtualizing disks to the containers (there is no virtual machine manager or hypervisor) the performance and efficiency of OS Level Virtualization is probably one of the best available on the market today.

OS Level VPS

Hypervisor VM

VPS Benefits

One of the most significant benefits in using a VPS is that there is less duplication of resources and much more efficient ways of using them. For example, each container does not require its own private kernel because they would all be identical, a single kernel runs on the base hardware node and is used across all containers. This type of efficiency reduces RAM consumption and Disk space across all containers and is not limited to just the Kernel. As a side note, having a single kernel also allows us to ensure that all kernel security patches are applied and kept up to date across all VPS's automatically. Our systems allow us to patch and update Linux Virtuozzo Nodes without the need for a host node reboot.
 

When to use a VPS

Even if you have a dedicated server, you will still want to give serious consideration to having a virtualization layer in place.  There are many benefits to this approach, and with OS Level virtualization having such a small overhead (1-3% compared with up to 20% for hypervisors) there are very few penalties. Probably the key reason that you will use a VPS is for the ability to run standard applications (apache, mysql etc) in a small sized container.  The memory and disk efficiencies of OS Level Virtualization will allow you to do much more with a VPS than compared to a VDS.

With Virtualization you get

• Live Migration, Zero downtime
• Simplified and faster kernel upgrades
• Higher VPS density and more efficient usage of resources
• In-Built backup tools
• Better VPS Performance, Lower disk and memory consumption

When not to use a VPS

• Because the OS Level is virtualized and there is a single kernel for all containers, you are able to only run Linux on Linux (Debian, Centos, Suse etc) and Windows on Windows. In the case of a dedicated server, you may wish to run multiple OS's (Windows and Linux on the same server) then you will not be able to use OS Level Virtualization. If you require a customized kernel or unique kernel modules then a VDS is more suited to your needs.
• Windows VPS's nodes require regular patching reboots. Windows VPS's utilize the underlying OS and by patching and updating the base OS, each container inherits these updates. This is great for most customers as they don't need to worry about patching, but if you want to have any level of customization or control over this then we would recommend a VDS.
• As a VPS uses OS Level virtualization, there are some things that you can do to break your VPS. For example, applying Windows updates (this is disabled by default, however you can still manually apply patches), attempting to modify the existing Linux Kernel, or attempting to significantly modify the NIC's.  If you want or need to have a true Virtualized Dedicated Server, then you should use a VDS.