from this article:
These are some of the large files:
A) gmapbmap.img (base map)
B) gmapdem.img (Digital Elevation Map, it’s per-region)
C) gmapprom.img (pre-installed map file)
D) gmapprom1.img (another pre-installed map file)
Maybe you backed them up, and replaced with map files from somewhere else?
Or just backed up your Edge 530?
I recently deleted my 530 backup. Can look tonight if you would like. Let me know.