Wednesday, 24 August 2011

Virtual Machine Clustering

Virtual Machine Clustering

Virtualization is a very popular concept today. The development of technology has pushed forward the realization that everything could be done online. Instead of a local installation on a gadget, an application could be used online which emulates the functions and even more when compared to local gadget. As long as there is a reliable connection, virtualization is possible.

Virtualization could even be implemented in clustering. Instead of physical computers or nodes, virtual nodes are created wherein each node has the same capability except that they are never physical. With the right configuration, clustering could be properly introduced to virtual machines to achieve stability and improvement of functionality. It may have some challenges and disadvantages but there are certain settings wherein virtualization in clustering an ideal solution.

Factors for Clustering in Virtual Nodes

Controlling virtual nodes will require virtual controllers as well. They are launched wherein the nodes are located so that communication is faster and control is instantaneous:

The most important “part” of virtual nodes is the host system. It could be a server or a machine where the virtual nodes are installed. The software that divides the nodes is part of the host system.

The guest system could be considered as the application that needs to be optimized when being run in different nodes. Since each node could work in a separate manner, optimization of the application could be easily achieved – even without physical nodes present.

Two control functions are also needed in clustering for virtual machines – the cluster manager and cluster service. The former are the identifying application for different virtual nodes while the cluster service is the application used to control the behavior of different nodes. These are practically the clustering application but would be for nothing if the first two systems are not present in the machine.

Advantages of Clustering of Virtual Nodes

Clustering virtual nodes could be easily applied to actual business scenarios. However, the advantage of clustering in virtual nodes is often based on its difference between physical nodes. When clustering is administered in virtual nodes, no additional hardware is required if the network administrator just wanted to have one server with multiple nodes inside the server. This removes the need to purchase additional hardware just to cater to the need of the clients. Instead of optimizing an application through various physical nodes, the network administrator could cut costs by only boosting the hardware on one server while installing multiple nodes.

Another advantage of virtual nodes is its ability to be totally transparent to the network administrator. Although physical nodes could provide transparency, control and monitoring is a lot easier through virtualization. Data could be easily accessed; control on different nodes is possible and troubleshooting is even easier.

The ease of troubleshooting is also another reason why clustering in virtual machines is easy. When faced with a very tough challenge in fixing the connection of a virtual node to another node, the network administrator could just discard that node and create another one. Since everything is done through an application, certain application could also be used to troubleshoot and repair the virtual node.

Disadvantage of Clustering for Virtual Machine

The problem in clustering virtual machines is not exactly on its software and configurations but on the fact that it lacks additional hardware. When the virtual nodes are launched in a single machine, consistency might not be achieved. The machine could go down and along with it are the virtual nodes installed in the machine. Since there is no physical back-up, the process could immediately stop and jeopardize the whole operation.

Ideal Configuration for a Virtual Machine

When a network administrator plans to develop clustering with virtual machines, it is highly recommended to observe HA (High Availability) form of clustering. However, instead of only two physical nodes, the each computer will contain identical virtual nodes. In case of failure of operations, the secondary computer could just take over with the same set of nodes. In this configuration, the number of nodes is still the same as the secondary physical machine will just take over.

Clustering virtual machines is cost efficient and highly transparent. However, reliability on the availability of the function could be easily jeopardized when the physical machine fails. For that reason, another physical machine should be in standby with the same nodes to prevent downtime.

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