L: is a 3GB partition on a USB attached 4GB disk.
Sounds a bit strange to me. I've not seen a 4GB disk since 15 years or so. Do you mean 4GB stick (ancient too) or 4TB disk? If you mean 3TB partition then this will never work with OS/2. At least not in near future. 2TB is max.
Actually the disk is from 1999 and it was pretty big in those days
But since it still works I can try various things out on it. You can pick up laptop hard disks at car boot sales for very little money these days - they are usually discarded after a Windows BSOD which costs more to fix than a replacement disk.
Obviously one problem is likely to be the presence of bad sectors and I'm looking for an OS/2 equivalent of SCANDISK.
I'm not sure if FORMAT detects bad sectors while formatting....