19-04-2012, 12:53 PM
Dynamic Load Balancing on Web-server Systems
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INTRODUCTION
Explosive Growth of the Internet
100% annual growth rate
Sites receiving unprecedented workload
Yahoo! 625 million views per day
AOL Web cache system receiving 5 billion requests per day
LOAD BALANCING
load balancing is a technique to spread work between many computers, processes, disks or other resources in order to get optimal resource utilization and decrease computing time.
A load balancer can be used to increase the capacity of a server farm beyond that of a single server.
A load balancer consists of a virtual server (also referred to as vserver or VIP) which, in turn, consists of an IP address and port.
virtual server is bound to a number of physical services running on the physical servers in a server farm.
A client sends a request to the virtual server, which in turn selects a physical server in the server farm and directs this request to the selected physical server.
SERVER
REQUEST PROCESSOR
server process the request
SERVER-LOAD BALANCER CONNECTION
a connection needs to be set up between
server and load balancer