The point of a cluster is to Increase the Capacity of your Dialer.
If you have MyZQL installed on a machine you are not using MyZQL, and an apache installed on a machine you are not using apache ... those services can be disabled at startup.
But attempting to install three (or eight) servers from scratch is not going to change the final outcome ... it won't operate different than the vicibox install with MySQL or apache turned off.
The "Master" server may have different applications "active for public consumption", but it and all the dialers still have a specific list of scripts and functions that are required.
So: Remembering that there are vicidial scripts that MUST run on ALL vicidial-related servers (except a MySQL box not being used for any other purpose) ... getting everything in place for those scripts to run (hi-res timing, no less, with ztdummy if necessary, perl scripts, everything) is not a simple task. Arguably, however, installing vicibox IS a simple task.
I suppose it would be possible, however, to modify the Vicibox install CD to "install only necessary applications" for a specific box use (Dialer vs Web vs Mysql). Although this would then limit the use of that particular box without further installation (instead of just re-activating the mysql, mysql would have to be installed).
Are you volunteering to create such a menuing system for the Vicibox install package
?
Personally, I think if you read the Cluster Installation methodology you will find that Vicidial's overhead (the scripts that MUST run) are the limiting factor on each box, not the "dormant" MySQL or Apache. So the present system is just right. But that's me.