[TriLUG] clustering or server mirroring

[Magnus Hedemark]

David McDowell wrote:

>One in the same?  Here's my idea.  I'd like to use CentOS 4 if
>possible to do this.  I would like to have my webserver mirrored on
>another machine so that if one goes down, the site continues to run. 
>If I change a config on one machine, the config should change on the
>mirrored machine.  Is this running a cluster or is this some other
>kind of setup?  Basically I have some time at work to play.  Any good
>resources for this kind of information?  Basically I want 2 servers to
>be identical mirrors of one another so that if one of the 2 goes down,
>I'm still online.  And, if I repair the broken one, it can resync
>itself so that the mirror of the 2 machines is identical again. 
>Suggestions, links, etc?
>

Since CentOS 4 is, despite what RHAT's lawyers say, technically pretty 
much RHEL 4, you can follow the admin docs for RHEL 4 to see how 
clustering works in there.  The way we're doing it at $WORK requires 
access to a LUN on a SAN that is unmasked to both servers, though, so 
I'm not quite sure how you would pull it off without some sort of shared 
external SCSI or SAN storage.