What is "MyFormat" and why are you using that? If using FFS, the tool built into the OS should work. If setting your partitions to PFS file system, use the appropriate PFS-format tool. I'd assume similar with SFS. Long story short, I don't generally advocate using any weird tools when it comes to disk operations. I think the hard files should show up transparently to the Amiga as hard disks, so HDToolbox and the built-in format command should get ya where ya need to go (assuming you're using something like 3.1 or preferably 3.9).
