Formal note: hard drives and filesystems used on hard drives have nothing to do with "iso". ISO 9660 is a filesystem for optical disks. A regular file containing a copy of an optical disk is often called "iso". Similarly (but incorrectly) some people call a regular file containing a copy of a non-optical disk (e.g. a HDD with Windows) "iso". It's just a copy, in Linux one can do it with
cp, it contains whatever the disk contains and it's not ISO 9660. So please clarify if by ".iso" you mean this must be optical media or its image; or if this may be a format better suited for HDD/SSD.