Freeze I/O on purpose like a vss snapshot
There are two undocumented DBCC commands you can use for this, on a test system of course.

DBCC FREEZE_IO('database_name');
DBCC THAW_IO('database_name')


Check out Erik Darling's blog post here, which is where I first heard about these commands: Wait Stats When VSS Snaps Are Slow

He's also using them to diagnose what behavior is like during these snapshot-related freezes.