I maintain a copy of the live system on-site, for problem replication,
training, etc which is refreshed from the live system on demand.

At my office I have a copy of the live system which I use for comparisions,
problem replication, etc and a development copy of the live system
where I make and test changes. Periodically I compare my 2 copies, generate
a difference script and apply to the live onsite system (after trying it out
on my live system) then replicate the live system to all other copies
throughout. All done via difference scripts and backup & restore

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Nick
-----We Solve your Computer Problems---
Founder & Listowner of the Prolifics User Group
Panther, Ingres, UNIX, Interbase, Firebird - Available Shortly