Linux Clustering Concept

Jephe Wu - http://linuxtechres.blogspot.com

Objective: understanding basic Linux clustering concept and tools
Environment: CentOS 5, FreeBSD 8


Concept:
1. What's the clustering
Connecting two or more computers together in such a way that they behave like a single computer.

2. 2 kinds of clustering 
parallel processing, and  load balancing

Parallel processing means the simultaneous use of more than one CPU to execute a program. Ideally, parallel processing makes a program run faster because there are more engines (CPUs) running it. In practice, it is often difficult to divide a program in such a way that separate CPUs can execute different portions without interfering with each other.

Load balancing means distributing processing and communications activity evenly across a computer network so that no single device is overwhelmed. Busy web sites typically employ two or more web servers in a load balancing scheme.


3. some example of web and application load balancing solutions
a. LVS - Linux Virtual Server at http://www.linux-vs.org
b. Pound - http://www.apsis.ch/pound/
c. PF carp and pfsync - http://www.openbsd.org/faq/pf/carp.html


d. tomcat connector - http://tomcat.apache.org/connectors-doc/