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Robert Nibali wrote:
> Ok, the second thing you'd like to know is how to check the service
> running on a realserver (please correct me if I'm wrong): I call this
> healthchecking (commercial loadbalancer vendors tend to call it alike)
> What you do here is: The loadbalancer runs a daemon that checks
periodi-
> cally all realservers services like for example http, telnet. This
check
> can be from poor-man solution (icmp) to highend (connect to webserver,
> start a request to the database and verify it's content). Your daemon
> then performes those checks agains all realservers and if a check
fails
> the realserver will be taken out. The check goes on and if the server
> or service comes back, it will be inserted again into the table with
> ipvsadm. NOTE: This works EXTREMELY well!!! Only negative aspect: You
> have to write your own daemon.
Several are availble, one in particular which comes to mind is, of
course, Big Brother (www.bb4.org or .com or something). It even
supports redundant monitoring, and services beyond the basics (e.g. ftp,
http) can be monitored with some effort.
Jano
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