Load balancing
UKFast's hardware load balancing solution provides the perfect antidote to the problem of hardware failure in an environment where downtime cannot be tolerated.
Load balancing is distributing processing and communications activity evenly across a computer network, so that no single device is overwhelmed. Load balancing is especially important for networks where it's difficult to predict the number of requests that will be issued to a server.
Busy websites typically employ two or more web servers in a load balancing scheme. If one server starts to get swamped, requests are forwarded to another server with more capacity. Load balancing also allows a solution to continue to function effectively even in the event of hardware failure.
Once the load balancer detects a problem with either one of your web servers, it will automatically take it out of the cluster and allow maintenance to be carried out. Once this work has been completed, the server can be put back into the cluster and allow load balancing to carry on as usual.
The load balanced solution is specifically designed to cope with one of a cluster of servers being taken out of the cluster without affecting the service that is provided to the users – giving you no single point of failure.
The cause of the server being removed from the cluster is not important in this situation. Whether the server has been removed for planned maintenance, a hardware upgrade or in the event of total failure, the solution will cope with its absence.
Essentially balancing works
- 1. A client requests a page from www.domainname.com
2. The load balancer forwards this request to one of a set of identical web servers.
3. The web server responds directly to the client unaware of any trickery.
The benefits of load balancing, in short:
If the load balancer detects a problem with one of your web servers, it will automatically take it out of the cluster until it is working again.If you need to perform maintenance you can take servers in and out of the cluster without effecting your clients.If the master load balancer fails the slave unit automatically and smoothly takes over. This solution can give you a complete no single point of failure solution
We offer two types of server load balancing, layer 4 and layer 7. The difference between standard load balancing (known as Layer 4) and Layer 7 load balancing is that with Layer 7 you read into the packet payload, rather than addressing information to determine the best place to send the traffic.
Types of Layer 7 load balancing
To carry out more precise load balancing, the content switch has to be able to look into the payload of the packet. The main decision-making parameters are described below:
- URL Parsing
- HTTP Header interrogation
- The User-Agent
- Cookies
- Better server efficiency
- High powered server experience
Because different types of content have different requirements in terms of CPU usage, I/O throughput etc, you can get better efficiencies out of your servers by grouping them so that some handle transactions, while others just act as massive storage systems for serving up static pages, or are optimised for downloading streaming video, for instance.
Layer 7 also allows for some users to be directed at higher-powered servers, if they are premium customers, or are on your site to place an order rather than just browse.
