| Load Balancer |
Article Index for Load |
Website Links For Load |
Information AboutLoad Balancer |
|
Load Balancing (performed by a '''load balancer''') is a type of service performed by a Computer that assigns work loads to a set of Networked computer Server s in such a manner that the computing resources are used in an optimal manner. INTRODUCTION A load balancer can be used to increase the capacity of a Server Farm beyond that of a single Server . It can also allow the service to continue even in the face of server down time due to server failure or server maintenance. 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 . This Virtual Server is bound to a number of physical services running on the physical servers in a server farm. These physical services contain the physical server's IP address and port. 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. Different virtual servers can be configured for different sets of physical services, such as TCP and UDP services in general. Protocol - or application-specific virtual servers that may be supported include HTTP , FTP , SSL , SSL BRIDGE, SSL TCP, NNTP and DNS . The load balancing methods manage the selection of an appropriate physical server in a server farm. Persistence can be configured on a virtual server; once a server is selected, subsequent requests from the client are directed to the same server. Persistence is necessary in applications where State is maintained on the server, such as a shopping cart application. Load balancers also perform server monitoring of services in a Web Server farm. In case of failure of a service, the load balancer continues to perform load balancing across the remaining services that are UP. In case of failure of all the servers bound to a virtual server, requests may be sent to a backup virtual server (if configured) or optionally redirected to a configured URL. For example, a page on a local or remote server which provides information on the site maintenance or outage. Among the server types that may be load balanced are:
|
|
|