Okay, so I burned that CD-ROM image four times now - twice on my Windows 
machine using CDBurnerXP, and twice on my Linux box using GnomeBaker, 
using various different speeds (last one at 1x). Wouldn't it be prudent 
to expect at least *one* copy to be good?

The only common things between the attempts (aside from the image in 
question of course, which is ok according to md5 checksum) are (a) the 
CD/DVD writer brand (both are LG, maybe even same model), and (b) the 
CD-R media brand and batch.

Last time I burned a CD-R was about a year ago. The CD-Rs are from the 
very same batch I used successfully back then, and they're still good to 
read. Is there something like "media rot" with CD-Rs specifically 
regarding being good for burning?

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On Mon, 16 Nov 2009 03:03:44 +0100, clipka <ano### [at] anonymousorg> wrote:
> Okay, so I burned that CD-ROM image four times now - twice on my Windows  
> machine using CDBurnerXP, and twice on my Linux box using GnomeBaker,  
> using various different speeds (last one at 1x). Wouldn't it be prudent  
> to expect at least *one* copy to be good?
>
> The only common things between the attempts (aside from the image in  
> question of course, which is ok according to md5 checksum) are (a) the  
> CD/DVD writer brand (both are LG, maybe even same model), and (b) the  
> CD-R media brand and batch.

1. Some models of burners do not work well with some brands/batches of  
discs.

2. Some brands/batches of discs are simply crap.



-- 
FE

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Fredrik Eriksson schrieb:

> 1. Some models of burners do not work well with some brands/batches of 
> discs.
> 
> 2. Some brands/batches of discs are simply crap.

Well, I'm using Verbatim media; I'd guess they're pretty common, and 
rated at "56x" (though I guess that's for reading only), so I'd be 
surprised if the burner wouldn't work with them reasonably at least at 
/some/ speed (I even went as low as 1x, but ironically that's when the 
burner ran into an error GnomeBaker categorized as "looks like buffer 
underrun").

And as for the discs, I had used up half of the cakebox already without 
any trouble.

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This looks like a case of "dirty CD/DVD recorder". Try to open it and 
gently clean the lens with cotton and some alcohol for about 30 secs, 
then with a dry tissue or peace of cotton "dry" it. It should work now, 
if this doesn't work, then probably the device "expired". IMO LG burners 
are the best they're, at least in my Country Bolivia.

Good luck.

Cheers.

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Saul Luizaga schrieb:

> This looks like a case of "dirty CD/DVD recorder".

Pretty unlikely, given that I tried on two different machines, with one 
of the recorders being short of a year old and seldom used, and the 
other being not even half a year old, and having been used successfully 
on some DVDs just recently :-)

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clipka wrote:
> Saul Luizaga schrieb:
> 
>> This looks like a case of "dirty CD/DVD recorder".
> 
> Pretty unlikely, given that I tried on two different machines, with one 
> of the recorders being short of a year old and seldom used,

Very fine and light dust settles on the lens exactly for this kind of 
use frequency.

> and the 
> other being not even half a year old, and having been used successfully 
> on some DVDs just recently :-)

Maybe just recently got dirty enough to stop burning correctly.

I'd recommend to open them and clean them every 2 months or so. BTW, do 
you use 'compare' option on the burning software? is really a lot of help.

Cheers.

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> This looks like a case of "dirty CD/DVD recorder". Try to open it and 
> gently clean the lens with cotton and some alcohol for about 30 secs, then 
> with a dry tissue or peace of cotton "dry" it. It should work now, if this 
> doesn't work, then probably the device "expired". IMO LG burners are the 
> best they're, at least in my Country Bolivia.

Yeh this is really rubbish - I cannot remember the number of CD/DVD drives 
I've had that have just lost the ability to burn or read discs.  Usually 
cleaning like you say helps for a bit, but they die eventually.  Maybe the 
room I keep my PC in is just too dusty, or I don't use the drives enough?  I 
wonder if optical media will die at some point and we can just use solid 
state memory?

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On Mon, 16 Nov 2009 05:00:02 +0100, clipka <ano### [at] anonymousorg> wrote:
>
> Well, I'm using Verbatim media; I'd guess they're pretty common,

Verbatim is usually the safest choice, but even they produce the  
occasional bad disc.



> and rated at "56x" (though I guess that's for reading only),

The rating is always for writing.



> so I'd be surprised if the burner wouldn't work with them reasonably
> at least at /some/ speed (I even went as low as 1x, but ironically
> that's when the burner ran into an error GnomeBaker categorized as
> "looks like buffer underrun").

Burn speed can have quite an impact on the stability of the burned data.  
Never burn at 56x; personally I would not go over 16x unless I planned to  
only use the disc once. However, modern discs and drives generally do not  
fare well with the lowest speeds either. Try to find a middle ground, like  
8x or 16x depending on the burner; you do not want to push the burner to  
its limits either.



> And as for the discs, I had used up half of the cakebox already without  
> any trouble.

It is not unheard of to get a few bad ones in a row; it has happened to me  
as well. A small hiccup in the manufacturing process probably.



-- 
FE

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I remember that when CDs where a new technology, they were really 
reliable and expensive, I still have working CDs burned a decade ago. 
They started making the CDs and now DVDs fragile to avoid piracy, it has 
some sense since back-uped or pirated data will only last a few 
weeks/months and won't spread much, but it ain't much of success is more 
a detriment than benefit.

CD/DVDs are meant for mass storage, solid state storage for mobile 
storage. People needs mass storage, solid state is just too young to 
provide it at low cost still, software should be harder to copy/back-up, 
so only user data can be mass-storage easily, thus no need to make 
crappy media, everyone wins.

Cheers.

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How do you know burning the image did not work?

Did you use the "verify" option of your burning program and did it fail? If 
so, try to eject the DVD and let it cool for a few minutes and then try 
again.

Or did you just try to use the burned DVD and it did not work? Then maybe 
the original image-file contains crap. Had this once, burned an image file, 
tried to open it, it did not work. Did it again, still did not work. Then 
looked at the image file using DAEMON tools and found that the data mastered 
in the DVD-image was invalid - the image file was OK, though.

Apart from this, if store CD/DVD improperly you can damage them. Never 
expose them to direct sunlight for any long period of time, never store them 
where it is too hot or too dusty.

Be careful where you put them - I once stacked some CD-R's one on the other. 
After a few years the cd-label marker I had used to label the CD-R diffused 
from the up-side of the bottom CD surface into the underside of the CD on 
top. I was lucky and the data was still readable, but this was a valuable 
lesson of "how NOT to do it".

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clipka wrote:
> Okay, so I burned that CD-ROM image four times now 

If it's a Linux image, it probably has a top-level menu option to check the 
disk. This (I believe) checksums each file individually, so you'll catch 
problems like the wrong files or missing files or something, even if the 
disk is burned correctly.  I've had that happen once - good burn of a bad 
Linux, for some reason.

-- 
   Darren New, San Diego CA, USA (PST)
   I ordered stamps from Zazzle that read "Place Stamp Here".

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clipka wrote:
> 
> The only common things between the attempts (aside from the image in
> question of course, which is ok according to md5 checksum) are (a) the
> CD/DVD writer brand (both are LG, maybe even same model), and (b) the
> CD-R media brand and batch.
> 

It is possible and I've *once* seen it happen, that the file is
corrupted and still gives the correct MD5 checksum. If possible, try
also another checksums (SHA-1 for example).

-Aero

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Fredrik Eriksson schrieb:

> Burn speed can have quite an impact on the stability of the burned data. 
> Never burn at 56x; personally I would not go over 16x unless I planned 
> to only use the disc once. However, modern discs and drives generally do 
> not fare well with the lowest speeds either. Try to find a middle 
> ground, like 8x or 16x depending on the burner; you do not want to push 
> the burner to its limits either.

16x is what I actually started with.

> It is not unheard of to get a few bad ones in a row; it has happened to 
> me as well. A small hiccup in the manufacturing process probably.

How many would that be, usually? Is it worth trying the remaining ~25 in 
  the box?

(Then again, maybe I should just try the one at the bottom...)

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TC schrieb:
> How do you know burning the image did not work?

Multiple symptoms:

* Verify of CDBurnerXP warned that verify failed in both attempts.

* Copying one of the CDs burned with CDBurnerXP to hard disk failed.

* Booting another computer from the CD (an openSUSE installation image) 
worked, but the inbuilt "check installation medium" (or whatever it's 
called) ran on a CRC error in one case, and some other error in another 
case.


> Or did you just try to use the burned DVD and it did not work? Then maybe 
> the original image-file contains crap. Had this once, burned an image file, 
> tried to open it, it did not work. Did it again, still did not work. Then 
> looked at the image file using DAEMON tools and found that the data mastered 
> in the DVD-image was invalid - the image file was OK, though.

Ran an md5 check on the image, and it was ok. Being an official openSUSE 
11.2 installer image, I guess Jim will confirm that we can rule out bad 
mastering :-)


> Apart from this, if store CD/DVD improperly you can damage them. Never 
> expose them to direct sunlight for any long period of time, never store them 
> where it is too hot or too dusty.

Hm, now that you mention it... I'm not sure, I /might/ have kept them 
for a while where they'd get a beam of direct sunlight for a few minutes 
on a sunny day. Not sure though.


> Be careful where you put them - I once stacked some CD-R's one on the other. 
> After a few years the cd-label marker I had used to label the CD-R diffused 
> from the up-side of the bottom CD surface into the underside of the CD on 
> top. I was lucky and the data was still readable, but this was a valuable 
> lesson of "how NOT to do it". 

They're still in the original cakebox; you'd expect that to be somehow 
suitable for storage of CD-Rs ;-)

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On Mon, 16 Nov 2009 20:48:20 +0100, clipka <ano### [at] anonymousorg> wrote:
>
>> It is not unheard of to get a few bad ones in a row; it has happened to  
>> me as well. A small hiccup in the manufacturing process probably.
>
> How many would that be, usually? Is it worth trying the remaining ~25 in  
> the box?

I have personally seen only 2-3 bad ones in a row, but since it  
essentially entirely random, there are two basic approaches: Keep going  
through the pile until one works, or assume it was a bad batch and throw  
away the lot.

Also consider that perhaps the burner just does not get along well with  
these discs; sometimes a firmware upgrade can help with that. Keep in mind  
that buying the same brand/label that you used before does not guarantee  
that the discs are the same.

Additionally, as TC pointed out, make sure the image itself is not bad.



-- 
FE

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Eero Ahonen schrieb:

> It is possible and I've *once* seen it happen, that the file is
> corrupted and still gives the correct MD5 checksum. If possible, try
> also another checksums (SHA-1 for example).

You've seen an MD5 checksum collision? Gee! You should be playing 
lottery ;-)

It also turned out later that the installer medium test failed with 
different error messages for different CD-Rs (yet same image); on the 
other hand, it did /not/ fail with the USB stick I later extracted the 
files to.

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clipka wrote:
> 
> You've seen an MD5 checksum collision? Gee! You should be playing
> lottery ;-)

A friend of mine hit it. Yes, it's extremely rare, but it's still possible.

And yes, I am playing lottery. Actually, on this year I'm still 6e oslt
on profit ;-).

> It also turned out later that the installer medium test failed with
> different error messages for different CD-Rs (yet same image); on the
> other hand, it did /not/ fail with the USB stick I later extracted the
> files to.

Ah, then the image should work. Just use the USB-stick? :-)

-Aero

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Eero Ahonen schrieb:

> Ah, then the image should work. Just use the USB-stick? :-)

Well, of course, that's what I did in the end.

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