Check for enough space before creating the backup to prevent failures due to full hard disc (Follow-up from "Add the GFZ deployment on staging and prod")

The following discussion from !2 (merged) should be addressed:

• @wilhelm.becker started a discussion: (+1 comment)

  Is it possible to check if there is sufficient space before the dumb is started? I assume the dumb creation to be costly and in case of a failure we want to keep the system running.