Erik Darling explains a process:
At some point you’re going to want to move some indexes to a new filegroup. Maybe you’re separating data across storage, maybe you’re cleaning up after someone who put everything on PRIMARY and walked away, maybe you’ve got your reasons and they’re none of my business.
Whatever the cause, you’d think this would be a solved problem in a database that’s been around since the Clinton administration.
It is not.
Some days, I’m convinced that the only way to win is not to play at all. Erik explaining how to migrate LOB data across filegroups fits that bill perfectly.