Load balancing

In Computing, load balancing is a technique used to spread work between many processes, computers, disks or other resources.

=Web server load balancing=

One major issue for large Internet sites is how to handle the load of the large number of visitors they get. It s routinely encountered as a scalability problem as a site grows. The ways to do this vary. One example of a site using the approach is the Wikimedia Foundation and its projects. In June 2004 the load was balanced using a combination of:

*Round robin Domain Name System distributed page requests evenly to one of three Squid cache servers. *Squid cache servers used response time measurements to distribute page requests between seven web servers. In addition, the Squid servers cached pages and delivered about 75% of all pages without ever asking a web server for help. *The PHP scripts which run the web servers distribute load to one of several database servers depending on the type of request, with updates going to a master database server and some database queries going to one or more slave database servers.

Alternative methods include use of layer 4 routers.

Linux Virtual Server is an advanced open source load balancing solution for network services.

Network Load Balancing Services is a Microsoft proprietary clustering and load balancing implementation.

=Vendors providing web server load balancing solutions=

*[http://www.coyotepoint.com/ Coyote Point Systems] *[http://www.f5.com/ F5 Networks] *[http://www.inlab.de/balanceng/index.html Inlab Software GmbH] *[http://www.kemptechnologies.com/ KEMP Technologies, Inc] *[http://www.netscaler.com/ Netscaler, Inc.] *[http://www.zeus.co.uk/ Zeus Technology]

= Vendors providing cluster, grid and HPC load balancing solutions =

*[http://clusterresources.com/ Cluster Resources]

=References=

*Tony Bourke: Server Load Balancing , O Reilly, ISBN 0-596-00050-2 *Robert J. Shimonski: Windows Server 2003 Clustering & Load Balancing , Osborne McGraw-Hill, ISBN 0-07-222622-6 *Jeremy Zawodny, Derek J. Balling: High Performance MySQL , O Reilly, ISBN 0-596-00306-4

=External links=

*[http://wwwcs.uni-paderborn.de/cs/ag-monien/RESEARCH/LOADBAL/ Dynamic Load Balancing and Scheduling] *[http://lcic.org/load_balancing.html Load Sharing and Balancing] *[http://www.zib.de/projects/telecommunication/STP/index.en.html Load Balancing in Signaling Transfer Points] *[http://sqlrelay.sourceforge.net/ SQL Relay] *[http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/6ac4a6ba-1c0c-46be-8c6a-2c2e0e567e98.mspx What Is Network Load Balancing] *Article [http://www.linux.com/article.plsid=05/07/27/1729229 Taking a load off: Load balancing with balance] by Costa Walcott *Paper [http://doi.ieeecomputersociety.org/10.1109/EDOC.2004.10020 Evaluating the Performance of Middleware Load Balancing Strategies] by Jaiganesh Balasubramanian, Douglas C. Schmidt, Lawrence Dowdy and Ossama Othman *[http://www.omg.org/gettingstarted/orb_basics.htm#g:LoadBalancing How does CORBA support load-balancing] *[http://citeseer.ist.psu.edu/cisq=load+balancing Citations by CiteSeer]