Hi Colin, Looks good - defaulting to 1MB boundaries seems to be a good safe option for all concerned. I hope the beta becomes visible soon so I can get a copy! That USB enclosure only reports SPC-2 and so it would not be expected to get READ CAPACITY(16) from the host to report sector size/alignment data. In fact with the current firmware, it will support READ CAPACITY(16) but does not fill in the sector/alignment bytes. If we added SPC-3 reporting and fixed the appropriate commands, are you saying that as a USB device, we will still never get the chance to return our parameters from READ CAPACITY(16) as the kernel will force the USB entity to be SPC-2? We are looking at how we can accommodate Advanced Format drives in USB in the US for our external drives. Cheers Steve Steve Perkins Field Technical Consultant Western Digital (UK) Ltd. Prime House,Challenge Court, Barnett Wood Lane, Leatherhead Surrey KT22 7DE +44 1372 366034