I know this is a much more 'techie' type of solution, but for an alternative to your methods, have a look at this:

Linear Feedback Shift Registers

LFSRs are basically very simple,...

Our problem has been fixed! Thanks for your help Jonathan and Markus. It took me some time to figure out what the hell was happening, but the method you suggested...

I'm not 100% sure this is going to solve my issue. I've still got the problem of having the mirroring potentially messing things up on the non-principal server. I'm looking...

Ooh, that looks like a good approach. I'll have a look at it first thing tomorrow and let you know how it goes. Thanks!