@gumetall There is no danger in even zero free space on majority of environments, PS3 included.
@Kevstah2004 You totally not understanding what this application doing... It reducing preservation threshold set on UFS2. PS3 don't using Linux but NetBSD fork (CellOS). And you not understanding how update process going. Update firmware packages are placed and unpacking on dev_hdd1. So you can update/downgrade fw with zero free space left on dev_hdd0.