EXAMPLES

Proxy Cluster

Configuration

• Each proxy server has its own disk for the cache pool
• Each proxy server set others as its sibling

Data Consistence

• each proxy server uses ICP protocol to query objects on other’s cache pool and fetch the object from others if needed
  

Web Server Cluster

Configuration

• Each web server has its own disk to store static datas (web pages, images)
• Common db server and nfs server in backend to store dynamic datas (customer input, session…)

Data Consistence

• Multiple copies of static data are maintained by administrator
• There is only one copy of dynamic data in central db/nfs server, no maintainance is required
  

Telnet Cluster

Configuration

• NIS is server used to store accounts for users
• NFS server is used to store the user homedir and mail spool(/var/mail)

Data Consistence

• There is only one copy of user data/mail, no maintainance is required

Mail Cluster

Configuration

• NIS is server used to store accounts for users
• NFS server is used to store the user homedir and mail spool(/var/mail)
• Sendmail daemon on each server must accepts mails targeted on virtual mail server
• Sendmail daemon on each server does masquerade on each outgoing mail as they were sent from virtual mail server
  

Data Consistence

• There is only one copy of user data/mail, no maintainance is required

Sendmail Setup

• Accept mails targetd on virtual mail server
  
  Search sendmail.cf, find a line like Fw-o /etc/mail/sendmail.cw
  Add the hostname of virtual mail server to sendmail.cw

• Masquerade outgoing mails as they sent from virtual mail server
  
  Seach sendmail.cf, find a line containing only ‘DM’
  Change the line to ‘DM you.virtual.mail.server’

WebMail Setup

• most webmail use a directory to store the session related information for each user. This directory must be put on the NFS server.
• some webmail use a directory to store the user preference setting, this directory must be put on the nfs server
• some webmail use a database to store account or session data, this data base must be accessable by all webmail server
• some webmail has support for lock over nfs on platform with incomplete nfs lock implementation, you may need to enable it if you are using FreeBSD or Linux as either nfs server or client
• an example of webmail: Open WebMail (http://turtle.ee.ncku.edu.tw/openwebmail/)
  • install this open webmail on all mail server
  • Open WebMail uses cgi-bin/openwebamil/etc/users to store user preference
    and uses cgi-bin/openwebmail/etc/sessions to store session related data,
    so the two directories must be put on the nfs server and each webmail server needs to make symblock to the one on NFS server
  • Open WebMail doesn't use a centeral database
  • enable the dot lockfile support if you are using FreeBSD/Linux as nfs server server or client