I’m not in front of a system where I can look, but I believe the DB is stored in /var/urbackup (file ends with a .db extension) If I recall, mine was almost 1.5 gigs. I don’t know exactly how many hours it took off hand, I know it was an hour between when I started it and when I left work - at that point it had gotten through an initial phase that didn’t show any progress information and onto the actual changes at which time when I left it claimed ~4% complete
Obviously, your HDD speed and system capabilities will impact this time.