Wednesday, 25 September 2019

Load Balancing Algorithms

A load balancing algorithm controls the circulation of approaching requests to your bunch of servers. There are various strategies utilized to finish this, contingent upon the unpredictability of load adjusting required, the sort of the main job, and the distribution of the requests coming in.

Some Common methods include:-
Round Robin:--

The most primitive load distribution technique. In a round robin scenario, the load balancer simply runs down the list of servers, sending one connection to each in turn, and starting at the top of the list when it reaches the end

Weighted Round Robin:--

It works on the same principle as Round Robin, but the number of connections that each machine receives over time is proportionate to a ratio weight predefined for each machine.
For example, the administrator can define that Server 1 can handle five times the traffic of Servers 2, and thus the load balancer should send five requests to Server 1 for each one request sent to Servers 2.

Least Connections
Transfers the latest session to the server with the least connections at the time of session initiation. To avoid latency, this method is advisable in an environment where server capacity and resources are uniform. Least Connections is considered problematic, as most implementations are challenged to accurately measure actual server workload.
In the above example Server 1 is handling only one request from (5) whereas Server 2 is handling 3 requests (2,4,6). Thus the subsequent requests will be handled by Server 1.

Weighted Least Connections
Identical to Least Connection, except that servers are selected based on capacity, not just availability. For each node, the admin specifies a Connection Limit value, and the system creates a proportional algorithm on which load balancing is based.

Least Pending Requests
The emerging industry standard, Least Pending Requests selects the server with the least active sessions based on the real-time monitoring. Requires assignment of both Layer 7 and TCP profile to the virtual server.
To achieve optimal load distribution and maximize performance, administrators must carefully weigh the pros and cons of their load balancing algorithms of choice.
                            


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