What are the Functions of Burst RAMs in Virtual Private Servers?

Virtual private servers are becoming increasingly popular for hosting websites, email and other internet services. One of the benefits of VPS is that it offers some of the benefits of dedicated servers without the high cost. One of the features of virtual private servers is burst RAM used as backup resource in the event of virtual server load.

Virtual Private Servers

Web hosts create virtual private servers by segregating physical servers into various virtual machines with each machine acting as a separate computer. This set up allows hosting servers to install their choices of operating systems and offers greater freedom to configure their VPS as they wish.

Web hosts on VPS can also install their own choices of software. Several virtual private servers can be hosted on one physical server making them much cheaper to rent than dedicated servers. Sandboxing allows each virtual server to be shutdown and restarted independently. This eliminates the chances of one VPS affecting other VPS running on the server.

VPS Resources

The physical server contains a piece of software called hypervisor that controls the creation and management of virtual machines and sets the amount of resources available to each machine. The amount of memory, disk space and CPU time allocated to each machine is determined by the hypervisor.

Burst Ram

While machines in a virtual server are allocated certain amounts of RAM, extra memory or Burst RAM is always available if needed. Burst Ram refers to free memory on a server that has not been dedicated to any particular machine or VPS and is usable by any VPS machine that requires it. For example, if a machine with 10GB memory used all its resources, it would be allowed to temporarily access a burst RAM of 5GB to boost its capacity. VPS can use burst RAM when the hypervisor cannot guarantee the machine’s RAM availability. Burst RAM is a temporary resource only accessible when allocated RAM resources are not available.


Burst RAM is useful for dealing with unusual circumstances to help the VPS stay online. For instance, burst Ram can prove useful when your site experiences a spike in traffic due to a celebrity’s post on social networking sites linked to your website. In such situations, burst RAM can enable the virtual private server to handle the extra load until the traffic subsides. Once traffic subsides, the hypervisor will return the burst RAM to its pool. It is advisable to increase your VPS’s dedicated memory if your server regularly accesses the burst RAM because the hypervisor cannot guarantee the availability of burst RAM.


There are three versions of hypervisors:
• Free open source

• Commercial open source

• Proprietary

Hypervisors work in different ways. Some allow web hosts to change CPU power and memory amount as and when needed. Hypervisors can only work on machines that have hardware virtualization enabled in the BIOS.

Web hosts with several identical servers can transfer VM from one server to another without service interruptions. VPS allows web hosts to set up high availability and load balancing for individual virtual machines or whole physical servers. Web hosts can also convert physical server systems to virtual machines using hypervisors.