Recently while working with a client, we have opted to look at the R2 upgrade from an existing R1 environment. It quickly became clear that there are a few things that can affect your upgrade experience:
1. Reference data will slow your upgrade down – This is a definite trade off that has to be made in the upgrade of FIM to R2. The synchronization engine has had major changes to how the reference data is stored to reduce the amount of time the system needs to process it. That said, if the environment being upgraded is dealing with a lot of referential attributes, this process can take a long time! The release notes have stated that this can take up to 5 hours and well, that was an optimistic estimate with as complex and environment as I’m dealing with right now. Having a test environment is a godsend for this as it makes it possible to provide an estimate of how long the FIM environment will be offline when moving to production. The trade off is that under R2 the system should process reference information much more quickly and therefore reduce your synchronization times. This is something everyone always wants but in the case of the R2 upgrade, there is a price to pay up front for you to realize the gain (and make sure the users of the environment understand that the system may be offline for a while).
2. Sharepoint Services 2010 Upgrade Issues – This was interesting as one environment upgraded fine and the other didn’t. In the case that I’ve been dealing with the system wouldn’t restart correctly and was hanging on the “Applying Computer Settings” screen. This was fixed by using the registry modifications noted in this technet article http://support.microsoft.com/kb/2379016
3. Plan an Appropriate Backup Strategy – This is standard operating procedure when you apply any patch or upgrade but is especially important in the case of the R2 upgrade. Remember that the upgrade is making significant changes to the underlying databases (so much so that I’ve seen one run for longer than 3 days!). Make sure a proper backup of the sync engine, fim service and databases have been captured. Rolling back if a failure occurred during the upgrade without these components will result in a lot of long hours and a ruined weekend or two. (Now is not a good time to test your DR strategy, make sure the backups are good prior to starting the upgrade!)