I've been trying to get a verified dump of a Dreamcast disc with DCdumper for the past month or so with no luck. I've tried with five different discs. I have two compatible drives for GD-ROM HD area dumping: a TS-H192C and a TS-H352C. Both reliably get matches on sections 1-39. They will both match section 40 occasionally (sometimes takes a LOT of passes), but not yet so that I have been able to verify any dump against the database. Also, I haven't been able to get the same hash on a section 40 match for the same disc twice.
From testing with my copy of Virtual On - Oratorio Tangram, I am certain that the drives are pulling good data from sections 1-39. This disc has 58 tracks on the HD area and I have been able to match checksums on the first 57 from multiple dumps. I've never been able to match the 58th.
I find it hard to believe that this is a problem with all five of my discs. None of them have any significant scuffs or scratches, and Virtual On is pristine. I've tried dumping with two separate PCs, with PowerShell and with the command prompt (not that I think either of these variables would matter).
Is this a common issue with Dreamcast dumping? Is there anything else I can try? Or should I really assume that both my drives are lemons? How many drives should I expect to go through before I find one that'll do the job with section 40?