We are planning to perform side by side upgrade of our Prod sql server from sql server 2008 to sql server 2014. Management team is requesting to keep two environments in sync for sometime, so that it would be easy to rollback or revert to old environment if we encounter any major issue. I am thinking of setting up replication with sync option replication support only. Is there any other possible solutions available as backup doesn't work over here in order to setup log shipping from 2014 to 2008. Our database size is >1TB Please advise.
I've done this myself at work using Mirroring, like Grant indicated. But it is a one way route. You can't go back via Mirror due the differences in version.
You have no other choice here because we are dealing with two different versions of SQL.
The key here is testing. Restore the database on the SQL 2014 box, point your app against that new SQL instance and test. Test again, and test more. And when you are done with testing, test again. There is no shortcut here for testing and even with enough testing, you will find pieces of code that need to be changed once you go live. So going back is not usually an option.
Give app team a deadline, let's say a week? But be clear that moving back means losing some work, usually not an option.