This week I encountered a puzzling issue when copying MySiteDB to a standby farm. Everything and everybody says it is simple. Well, not today.
Set up standby farm userprofiles and all is well. Copy MysiteDB over, ask user to login and then access his MySite and... weird permissions FAIL errors.
After numerous attempts at clarifying the permissions of the user, ensure he is Site Collection Admin, the app-pool has dbo, etc. we started to reset the user account and I noticed that the site collection admin for the users mysite was showing as a claims pattern instead of domain\user. Hello, hello. Checked and yes, the web-app on the Standby farm was using claims. Go back to production and aha! using Classic auth (Kerberos).
Recreated standby farm mysites host web-app with Classic mode. copied source MySiteDB to standby farm and... everything works immediately. whew!
In SharePoint 2013 there is a handy cmdlet Convert-SPWebApplication which could have been useful if it had been available.