[MacClipper]

Just thought of another way of approaching the subject matter which is hopefully more direct and constructive making it easier to understand for the casual reader. I think there are enough threads detailing which media is bad etc running into pages and pages referencing innumerable websites... this thread is more about media which has been shown to survive ie. Got Scan Can Talk!

CRITERIA
1. Media must be burned more than 6 months ago
2. 0 media sense errors
3. passed Transfer Speed test (a nice to have but optional requirement since standalone DVD machines play at only 1x speeds)
4. 0 PO Failures (? importance since POF doesn't always mean that the data is unretrievable)

SCANNING SETUP
1. Scanning burners - BenQ DW series (8x scan speed) recommended eg. 1620/1625/1640 since they can report PO failures (and jitter too). Other burners like Liteon (4x)/NEC (5x) models can also do error scanning but without PO Failure reports.
2. using CD-DVD Speed (freeware, latest version is 4.01), Click to download

If you do not own a BenQ DW16xx series burner, you are still welcome to post your scans too using other tools eg. good CD-DVD Speed Transfer Curves for non-error scanning models eg. LG burners.

You are also welcomed to add your own comments on the disc/media eg. rate of survival, label surface durability, pictures etc...

REASONING
If a disc can be read or scanned without CRC errors, data integrity is preserved at that moment in time and it is considered a survivor at that time. Let's not clog up this thread with arguments about how smooth or pretty a reading curve needs to be or how many times the disc needs to be read to get the data off. Let's keep it simple, clean and to the point here so thread readers do not have to pore through the whole thread just to get what's going on.

I will posting the scans of my own discs which has been stored in spindle cases (pressure effects) by my room window which is exposed to sunlight (UV exposure as well as increased heat). No special care has been taken of them cos I wanted to see the effect of accelerated ageing on the discs (which has no impt unique data, of course).

The scans will run against the current mood in this forum which has repeated ad nauseum that DVD media cannot survive long term - so I am prepared to be accused again of having a vested interest in optical media industry. Just for clarity, I am not in this or any IT related industry at all, my main line is totally non-related as those who know me on a personal basis can attest.

btw, bad scans does not always equate disc degradation cos you can always get a fresh bad burn (with a bad scan).



Advisory
Anyway, just a little sidetrack to clarify my own stand that I am just a ODD fan without any commercial interests cos I am not even in the IT line at all. Here's MichaelTan of Convergent himself in his own words,

VR-Zone IT & Lifestyle Forum! - View Single Post - Hello People.
from this thread, click


Oh well, that's for all it's worth.

3 cheers to ColdFusion for all the hard work (took him many days of hard work to port this over), hope it benefits others who are looking for lasting DVD storage as well.

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Originally Posted by MacClipper

April 2003 - Apple 2x MXL DVD-R (the 4x version has almost 100% failures after 6 months)

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Originally Posted by MacClipper

Sept 2003 - Verbatim 2x DVD-R (batch prone to POF at the periphery)

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Originally Posted by MacClipper

Oct 2003 - Verbatim 2x DVD-R (batch prone to POF at the periphery).

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Originally Posted by MacClipper

Sept 2004 - Maxell 4x@8x DVD-R (no problems noted so far)

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Originally Posted by MacClipper

May 2004 - TDK DVD-R (forgot which speed rating liao, no mention on the label)

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Originally Posted by MacClipper

July 2004 CyberDVD 4x DVD-R

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Originally Posted by wwenze
Just asking, passing transfer speed test = perfect graph?

Originally Posted by MacClipper

Fair enough a question, as long as a media can pass a transfer test, the disc is deemed readable (and thus a survivor) so the curve does not have to be perfectly smooth. An error scan would definitely be more informative but in lieu of that, a successful transfer curve would suffice if you lack a scanning burner.

PS: ANY speed above 1x would do cos standalone players only run at 1x speed for movie playing. Besides, there is always the riplock to think about which results in diff. max speeds among different burners and not all burners have riplock free modded firmware.

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Originally Posted by MacClipper

Jan 2004 Verbatim 2.4x +R,

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Originally Posted by MacClipper
Fair enough a question, as long as a media can pass a transfer test, the disc is deemed readable (and so a survivor) so the curve does not have to be perfectly smooth. An error scan would definitely be more informative but in lieu of that, a successful transfer curve would suffice if you lack a scanning burner.

PS: ANY speed above 1x would do cos standalone players only run at 1x speed for movie playing. Besides, there is always the riplock to think about which results in diff. max speeds among different burners and not all burners have riplock free modded firmware.

Originally Posted by p4overclockerII
However, a transfer rate curve which dips down for a considerable segment severely at the end or shows a constant low speed read withs ups and downs and never reaches the expected ideal curve implies deterioration or degradation.

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Originally Posted by p4overclockerII
I will be doing a mass scanning of my April 2005 batch of dvd discs in end December 2005 (this year). This batch of discs are stored in dry boxes with silica gel with conditions that are supposed to protect the discs. I hope to get good news from this batch of discs because by the time of Dec 2005, they will be already 8 months old. Hence, IF majority of this batch of discs shows no degradation or errors in Dec 2005, I will have a lot of surviving discs to add to this thread.

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Originally Posted by MacClipper

I believe that as long as a disc is readable without CRC errors when scanned or read, data integrity is preserved at that moment in time and data integrity is the main point in data archival, not pretty scans or smooth transfer curves.

And for movie DVD backups, the main usage for a lot of people using recordable DVD, the movie should play back smoothly if you can get a perfect 1x transfer curve. Maybe you can do and post for us 1x transfer curves for those discs which do not have smooth max speed transfer curves.

How about it? We need someone with that kind of tenacity and with lots of time on his hands since 1x transfer curves (or even better, 1x error scans if that is possible) are going take an hour each. The good thing is that any DVD drive will do for 1x reading curves, even plain DVD ROMs for this test.

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Originally Posted by MacClipper

July 2004 TDK 4x DVD+R,

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Originally Posted by MacClipper

I believe that as long as a disc is readable without CRC errors when scanned or read, data integrity is preserved at that moment in time and data integrity is the main point in data archival, not pretty scans or smooth transfer curves.

And for movie DVD backups, the main usage for a lot of people using recordable DVD, the movie should play back smoothly if you can get a perfect 1x transfer curve. Maybe you can do and post for us 1x transfer curves for those discs which does not have smooth max speed transfer curves.

Originally Posted by p4OverclockersII

DVD readers can have many read retries and read slowdowns to get a perfect read off the dvd without errors. But the disc has problems (i.e. degrade) (even without errors) because the reader has to do many read retries and read slowdowns. We are NOT looking for perfect or pretty graphs but this is a basic understanding that a disc has problems if several readers used have to employ many many read retries and read slowdowns to get data off the disc without errors.

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Originally Posted by MacClipper

July 2004 TDK 4x DVD+R,