Wednesday, 24 August 2011

Load Balancing Clustering

Load Balancing Clustering

Every business wants to ensure their online operations such as their e-store or online application for customer service works well anytime of the day. They need to have powerful servers, applications and the right clustering to ensure a fail safe operation for their users.

Clustering pushes the functions of an application to be faster or ensures data availability’s faster transfer. With the right clustering form, online or network (for local use) needs could be easily serviced.

An ideal clustering form to ensure stability is load balancing. Clustering by load balancing is basically a form of connection between computers (referred to as nodes in clustering) wherein the workload is evenly distributed.

Although a single computer could provide the same operations, the hardware capability of a single computer or a node will never be enough to handle massive data requests and processing.

To answer to the constant requests, multiple computers are connected together to harness each processing power. By sharing the workload, the processing time is increased and massive data requests and processes could be possible.

Load balancing is a form of clustering often differentiated with High Availability (HA) clustering. HA Clustering is a form of connection between nodes wherein a primary node is backed up with a number of nodes in case the primary node fails.

Load balancing and HA aims for one thing – stability. Their configuration ensures that the features of an application will always be available or the data will always be there when the customer needs them. HA aims to do that by having multiple back-ups while load balancing ensures stability but getting multiple nodes to work at the same time.

Transfer of Workload

One feature that would make load balancing stand-out is its ability to address failures. Every machine will always reach its toll and the only way to address them is to have a ready solution in case this happens.

In load balancing, the workload of the failed node is immediately redistributed to other nodes. By distributing the workload, efficiency continues since the nodes will only experience relatively small changes.

Workload transfer is done once the node fails as the load balancer connects to the nodes works like a pulse that monitors the performance of each node. With a predetermined interval, the load balancer will check each node and alert the network administrator in case one node fails. Balancers in load balancing cluster have the ability to transfer the workload to other nodes automatically to avoid further delay of operation.

Prevention of DoS Attack

Another feature load balancing brings to businesses is the ability to prevent attack by DoS (denial of service). This type of attack could be done by multiple computers wherein constant and high data requests could easily use up the bandwidth of the website. Through consistent high data requests, the online application will not be able to service the legitimate users. With only a single node through a server answering the computation, DoS could be experienced by legitimate users.

Load balancing should be able to handle this attack without any problem. Consistent and high data requests could be easily handled by multiple nodes as the load balancer evenly distributes data requests from different users. Delay binding could even be implemented by load balancers wherein the requests are not answered together but some are delayed to ensure stability of the functions.

Hardware Requirements

For load balancing to work, additional hardware is required wherein its sole purpose is to continuously monitor nodes and redistribution of workload if one of the nodes fails. Some see this as a disadvantage for load balancing cluster since it will require additional spending just to ensure the nodes will be working well.

But this additional hardware is actually a better configuration especially for businesses who expects massive traffic for their online services and data. With the help of an additional hardware, the nodes could fully focus on ensuring the functions work well or the data will be transferred as soon as possible.

HA clustering on the other hand will require the nodes to constantly monitor the primary node and take over if the primary node fails. Load balancing may cost more compared to HA clustering but the additional hardware will optimize the nodes in this clustering design.

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