How You Practice the Upgrade
You should run a trial upgrade as early as possible in the conversion cycle. Ideally, trial upgrades should be run more than once. Doing so helps identify and isolate problems, and also supplies timing data, which will be useful when the production system is upgraded.
A simplified upgrade process is as follows:
1. Run a trial upgrade.
2. Take notes on what went wrong or what should be done differently.
3. Continue running trial upgrades until no more problems are encountered.
4. Give the annotated upgrade procedure to someone who can verify the upgrade plan.
Note: Perform at least one of the trial upgrades on a full live data set, which will give an indication of how long the upgrade will take. This is particularly important when doing an unload/reload upgrade.