Unusual burn rings after a write failure of a DVD-R

Sean 2012-07-22 16:22:43 UTC #1

While we had visitors earlier today, one asked if I could transfer her photos to DVD so she should free up space on her card. So I copied them to my PC and wrote them using ImgBurn. From past experience, I always check the 'Verify' option and in this case it sure prevented a problem as the verify stage failed 1/3 through the disc despite not having a coaster for quite a long time.

To my surprise, when I looked at the bottom of the disc, this is what I saw:

I'd not sure what to call these, "Rings of death"? :bigsmile:

For anyone curious, the disc is a Verbatim 16x DVD-R, MID is MCC 03RG20, written at 16x and the DVD writer is a Samsung SH-S223B.

After this, I got another disc and it wrote and verified successfully.

Has anyone else encountered ended up with a coaster with unusual rings or patterns on the recording surface? Despite numerous coasters in the past going back to the days of my first 2x SCSI CD-RW drive, I've never seen a coaster like this before.

Albert 2012-07-22 17:32:19 UTC #2

It happens when drives are unable to adjust laser power accordingly when they run across a disc flaw, or when the drive is trying to write too quickly and gets erroneous information during an OPC check. Occasionally, it will happen with an overly-aggressive OPC algorithm on a perfect disc. The drive can keep going with no issue due to the fact that the drive hasn’t completely lost tracking, focus, or the overall location address as it writes, but the drive doesn’t know that it caused a fatal issue; at the next OPC checkpoint (possibly while still within the defective region of a disc), the drive will adjust itself back into the normal range for the disc being written and not even flinch, maybe slowing itself down (at worst).

In this case, it was a disc flaw combined with the high-ish write speed. Once you get the initial ring, there may be more successive rings (as you see) depending on the drive’s burning strategies, or depending on the extent of the disc flaw.

I’ve seen it happen with LiteOn drives, LG drives…it can be tiny rings, or huge sections of the disc just appear to be completely unwritten.

CDan 2012-07-22 19:14:37 UTC #3

Look closely at about 9:00 on the 1st ring. See a dark area? That’s the flaw in the disc that caused the failure.

Wombler 2012-07-23 00:24:21 UTC #4

Some drives alter the write strategy at different stages throughout the burn and this produces banded rings that can be very clearly visible on certain media. Banding is perfectly normal for drives that operate in this manner and in fact it increases quality as the write strategy is optimised across each section of the disc.

CDan is correct, it’s the dark area that has caused the failure.

[B]Wombler[/B]

Sean 2012-07-23 01:19:59 UTC #5

I see the defect now. The discs have an inkjet surface, so it’s not visible on the top side.

On the other hand, I have seen rings of different shades (e.g. 1/4 one shade, next 1/4 slightly lighter, etc.), but I’ve never seen anything stand out like the above before. That’s what I call a coaster.

Albert 2012-07-23 05:21:00 UTC #6

^you usually can’t see defects like that from the top of the DVD in any case. That’s why we around here are eagle eyed and stare at the data side for days under clean room conditions.

Arachne 2012-07-23 06:15:20 UTC #7

Yep, agree with Albert and CDan.

[QUOTE=Albert;2645123]^you usually can’t see defects like that from the top of the DVD in any case. That’s why we around here are eagle eyed and stare at the data side for days under clean room conditions. [/QUOTE]

Yeah, I bet if asked a lot of us in here wear glasses or contacts, if only for inspecting discs…errr I mean reading.

LOL @ SeÃ¡n’s “rings of death” - I can see that term catching on