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What is considered good enough in tests

Postby SuperG on Mon Mar 17, 2003 4:58 pm

Hi ALL,

I am a little new to the testing of CDRs. So if anyone could tell me using Nero CD Speed, what results are considered very good, good, OK, bad, and very bad. And also, if I can use this CD Doctor program I hear so much about. I am not sure it is compatible with my drive. Well lets start with an example and then someone can give me their opinion. I have a 74MIN 650MB TDK, burned over 2 years ago, and stored in good condition, with no visible marks/discoloration on it. The actuall written length is 71mins, and 627MB, and its a DATA CD. With ATIP: 97m 24s 01f
Manufacturer: Taiyo Yuden Company Ltd. Recording Layer: Cyanine Material.
And I know that Taiyo Yuden is suppose to be among the BEST for quality CDRs.

I decided to pop this into both my CDR/RW dirve, which is a Ricoh 7200A, and my regular 50x MAX CD-ROM, of which I do not know the brand, nero cd speed just says "E-IDE CD-ROM 50X L V15".

First, for my CD-ROM, using CD Quality Check on Nero CD Speed, and it reported, 458,640 Errors (with 3 red spikes through the majority of the disc, and as many a 6 red spikes directly at the end of the disc (maybe because the CDR is not finalized???)). Then with my CD-ROM and Nero CD Speed ScanDisc, running both the filetest and the surface scan. For the File Test, it gave the result, files checked: 21 / Errors: 0. As for the surface scan, I got the result: 98.83% Good, 0% Damaged, and 1.17% Unreadable.
Next, for my CDR/RW drive, using CD Quality Check on Nero CD Speed, and it reported, 0 ERRORS!!! (no spikes). Then with my CDR/RW and Nero CD Speed ScanDisc, running both the filetest and the surface scan. For the File Test, it gave the result, files checked: 21 / Errors: 0. As for the surface scan, I got the result: 100.00% Good, 0% Damaged, and 0% Unreadable.
I am a little confused as to how my burner returned NO ERRORS AT ALL, but my regular CDROM reported 400000+ errors, and the unreadable sectors.

Now after seeing all this, I am guessing since the burner read it perfectly, the CDR is fine, but why the difference between my CDROM and CDR/RW. And does that mean anything for the longevity of my media? Also, assuming I am using my CDR/RW for my tests, what is considered acceptable for my other media? Is less than 100,000 errors good enough? less than 50,000?, or does it have to be 0 errors? And how does the surface scan need to be, generally, ?% Good, ?% Damaged, and ?% Unreadable. I have a lot of important stuff already stored on CDRs, and back then, I did not know much about quality of CDRs, I just picked up what I could find. So therefore, I would like to test my CDRs, and move the data onto different CDRs, if there is a problem with them, before they die out completely. Also, are all of these tests required before you can make a judgement on that CDR, or is it OK if the first test has no errors, can you determine that it is OK? For example, if I run the CD Quality test first, and I get a result of 0 ERRORS, then is there still a need to run the file test and surface scan? And in the same way, what if I ran only the Surface Test first, and it gave me 100% Good, do I still need to run the file test and the CD Quality Test? Thank You.

SuperG

P.S. Also, please let me know if I can use CD Doctor with my CDR/RW or my CDROM. Thanks.
SuperG
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Postby cfitz on Mon Mar 17, 2003 9:41 pm

Your drives do not support CD Doctor.

In CD Speed's tests, I consider a good result to be 100% green (no errors at all). That is the criterion we use for the media compatibility thread here.

A few damaged sectors is something you can live with if you must, but not something I would put up with if I had a choice. I would switch media if I found that my discs were regularly showing damaged sectors.

No level of unreadable sectors is acceptable (with the exception of the very last sector if the disc isn't finalized). Why? Because unreadable sectors mean data loss.

Errors are not a function of the media alone. The burner, the speed with which the disc was burned, the reader and the speed at which the disc is read are all contributing factors. So it is possible to have a disc test out good in one drive but bad in another. In your case with the disc showing actual read errors on one of the two drives with which you tested, I would like to test with at least one more drive to get a best-of-three consensus.

When testing on your Ricoh drive, did you get any messages about the drive not supporting C2 error testing? I think it does, but am not 100% sure. If it doesn't, then any disc you test won't show any damaged sectors (although it can still show unreadable sectors).

cfitz
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Postby SuperG on Tue Mar 18, 2003 2:22 am

cfitz,

Thanks for your response. Well I guess if CD Doctor is not supported, then I won't try it. When you say in CD Speed's tests, 100% green is good, do u mean the surface scan, or the quality scan?

As far as C2 errors is concern, I believe my drive does support it, because in Feurio, the C2 error reporting box is CHECKED stating that it supports it. However, could it be wrong? Because I have never seen a CDR report any damaged (yellow) squares, on any CDR i have checked. However, I have not checked very many, and the ones I did, were all in good condition. Is there anyway for me to make a CDR "partially damaged", so that I can put it in my CDR/RW and check to see if it is reporting it correctly? But I have had a couple of CDRs, where there were a few Unreadable (red) squares reported by my CDR/RW using scan disc. They were at different spots throughout the disc. Does that mean it does support C2 error reporting for sure? And finally, as I asked in my first post, is the scan disc test enough to assure me that the CDR is fine, and that I shouldn't transfer the data from that CDR to another? Thanks.

SuperG
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Postby cfitz on Tue Mar 18, 2003 2:53 am

SuperG wrote:When you say in CD Speed's tests, 100% green is good, do u mean the surface scan, or the quality scan?

Either/both. They are both measuring the same errors and just presenting the data differently, so if you get zero errors on one you should generally get zero errors on the other. (The noise portion of errors is a random process, so there is some small chance that an error pops up on one test but not on the other, or on one iteration of one test but not the next iteration when the test is repeated.)

SuperG wrote:As far as C2 errors is concern, I believe my drive does support it, because in Feurio, the C2 error reporting box is CHECKED stating that it supports it. However, could it be wrong?

Occasionally a program can make a mistake reporting a drive’s capabilities, often because the drive itself misstates them. But I've now seen enough different sources saying that your drive reports C2 errors (including your own report) that I believe that is accurate.

SuperG wrote: Is there anyway for me to make a CDR "partially damaged", so that I can put it in my CDR/RW and check to see if it is reporting it correctly?

Sure, take a CD you don't care about, and scuff the bottom surface, or scribble some marks with a permanent marker, or leave it outside exposed to direct sunlight for a while. Scratching and marking is easiest. Start with just a little damage, then test, and damage your disc some more and test again.

SuperG wrote:But I have had a couple of CDRs, where there were a few Unreadable (red) squares reported by my CDR/RW using scan disc. They were at different spots throughout the disc. Does that mean it does support C2 error reporting for sure?

No. Special support is needed to report C2 errors because they are typically corrected before they make it out of the drive. So, if the drive doesn't specifically state that it found and corrected errors, there is no way for the outside program receiving the data to know anything was wrong. On the other hand, all drives can "report" unreadable data, simply by the absence of the data that could not be read.

SuperG wrote:And finally, as I asked in my first post, is the scan disc test enough to assure me that the CDR is fine, and that I shouldn't transfer the data from that CDR to another?

If the disc shows all green, then yes that is sufficient. It's nice to have C1 error data as well (as shown by CD Doctor) because elevated C1 levels can be indicative that soon there will be C2 errors, which themselves have a tendency, when they become elevated, to be become uncorrectable errors that lead to data loss. However, C1 data aren’t necessary. You could think of C1 data as just an additional level of early warning.

A useful adjunct you might want to try for checking your discs and assuring yourself that all is well is CDCheck:

http://www.elpros.si/CDCheck/

It can be used to verify the integrity of all the files on your disc. Unfortunately, because CDCheck works at a higher level than CD Speed’s scan disc/CD quality tests, by the time CDCheck finds a problem, your disc already has at least some "uncorrectable" errors and "unreadable" sectors. But this doesn't mean all is lost. Often slowing down the read speed or reading multiple times can recover the data if things haven't gone too far wrong. CDCheck includes both detection and recovery tools, and thus acts as an additional insurance policy.

cfitz
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Postby SuperG on Tue Mar 18, 2003 3:18 am

cfitz,

Thanks again for your reply. Now I guess I have just a couple questions left. First, does my burner support C1 error checking? And second, when I check CDRs, should I use my Burner or my CDROM? BTW, according to Feurio again, my CDROM ASLO supports C2 Error Reporting, but again it could be wrong. The reason I want to know which drive to use is, as in my first post, I got totally different responses from each, one perfect and the other many errors. So what should I use? Thanks.

SuperG
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Postby cfitz on Tue Mar 18, 2003 11:34 am

SuperG wrote:First, does my burner support C1 error checking?

No.

SuperG wrote:And second, when I check CDRs, should I use my Burner or my CDROM? BTW, according to Feurio again, my CDROM ASLO supports C2 Error Reporting, but again it could be wrong. The reason I want to know which drive to use is, as in my first post, I got totally different responses from each, one perfect and the other many errors. So what should I use?

As I mentioned, you will get different results with different drives. And, as I mentioned, in your particular case since you got such drastically different results between your two drives, I recommend that you test your discs on at least one other drive (borrow a friend's computer, try it at work, etc.) to get a feel for which of your two drives is more representative of an "average" drive. After you have done that for a few discs and have determined which of your drives is more representative of an average drive, then you can stick with testing on just that drive. I suspect that your CD-ROM is having problems, and that the Ricoh CD-RW is the better choice to use for testing, but you really need to test your discs on some other drives before concluding that this is the case.

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