I am planning to upgrade from SQL 2008 R2 SE to SQL 2012 SE in our prod env. The upgrade will be an inplace upgrade to a cluster environment from standalone. I ran the upgrade advisor and I got no unresolved issues. I already did this on our staging and test environments and upgrade was successful. But the thing is I havent noticed any performance improvement. However after upgrading it from 2008 R2 SE to 2012 SE in our production environment and after a day/two of monitoring if we notice a decrease in performance and then if we decide to rollback I will have to rely on restoring the full backups that I took before the upgrade process. But a day/two's worth of data is in the 2012 database and I will have to do a data compare and move over the new records to the 2008 R2 database. And the databases are almost a terabyte and this is going to be a slowprocess.
Can experts please share their inputs for a better rollback plan inplace of upgrade failure or upgrade rollback.
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