BU files in B1_SHR

Hi,

The question might be very simple, but being new to SAP, I don't know the answer.

What exactly are those .BU files created in B1_SHR and occupying to much space? The reason I am asking is because up until 10 days ago there was nothing like that generated. All of a sudden, i am seeing huge 6GB .BU files generated in that folder. Looks like it's some sort of database backup files.

Can I delete them?