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CD and DVD Unreliable for Critical Archives

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Anonymous
December 27, 2004 1:13:22 PM

Archived from groups: rec.video.desktop (More info?)

Many of my older CD-R's are partially unreadable now, and a new DVD-R
is also partially unreadable. As a result, I have little faith in this
type of media for critical storage, and I am leaning towards buying
lots of hard drive storage so that I can keep a copy on optical disk as
well as magnetic disk. My intuition is that a quality hard drive that
is only used occasionally will probably outlast me.
Anonymous
December 27, 2004 4:07:50 PM

Archived from groups: rec.video.desktop (More info?)

BrianEWilliams wrote:

> Many of my older CD-R's are partially unreadable now,
> and a new DVD-R is also partially unreadable. As a result,
> I have little faith in this type of media for critical storage,
> and I am leaning towards buying lots of hard drive storage
> so that I can keep a copy on optical disk as well as magnetic
> disk. My intuition is that a quality hard drive that
> is only used occasionally will probably outlast me.

Make sure you double the hard drive storage, and parallel
your archives -- at least. I would also use optical storage
as part of that long-term plan. If you truly have "many"
CD-Rs that have failed, then I would question either the
storage method or the media that you're buying.

In addition, you need to make sure you have a good index
to all your data, and periodically look for file formats that
are going out of favor, and translate those files into newer
protocols. Same goes for applications.

Archiving ain't easy -- it's hard work.
Anonymous
December 27, 2004 5:18:11 PM

Archived from groups: rec.video.desktop (More info?)

A hard disk is possibly the LEAST secure backup for critical data.
Exposure to magnetic fields, temperature, humidity will all cause
degradation of the unit. Dropping it is particularly bad.

If you find problems with your backup media it would seem you need to
attempt to identify the causes of the failures.

Some obvious flaws are:
1. never written correctly in the first place. My Nero cd writer will
write a disk but enless you specify a validation after write it may be
flawed.
2. Label with a solvent based marker. (not water) may after time etch
into the disk surface.
3. Label with a paper label with wrong adhesive type. Similar problem
to markers.

Some products do not assume you can read a cd years after it was
created.

4. Storage
This seems to attract some dispute about proper methods.
I use an archival grade paper envelope stored vertically in a case. The
paper envelope limits air exposure.

Good luck with your problem.

PS
It seems odd that when CD's were first being promoted that the music
industry claimed you did not need to worry about scratching them since
it was a digital media and any scratch would be trivial when it came to
playback. They showed them being tossed about like frisbies, used as
drink coasters and then playing perfectly.
Maybe they used better plastic back then.
Related resources
Anonymous
December 27, 2004 5:26:36 PM

Archived from groups: rec.video.desktop (More info?)

On 27 Dec 2004 10:13:22 -0800, "BrianEWilliams"
<sorry_no_email@yahoo.com> wrote:

>Many of my older CD-R's are partially unreadable now, and a new DVD-R
>is also partially unreadable. As a result, I have little faith in this
>type of media for critical storage, and I am leaning towards buying
>lots of hard drive storage so that I can keep a copy on optical disk as
>well as magnetic disk. My intuition is that a quality hard drive that
>is only used occasionally will probably outlast me.

It's always been my understanding that hard drives are one of the
least reliable pieces in a computer. They *will* break eventually, and
usually right after you *should have* done a backup.

It's my serious opinion that critical archives need attention. With
digital data, we are somewhat limited in that a paper printout is
pretty much useless, so we need to be on top of whatever new
technology comes out.
CDs /DVDs need multiple copies; that's pretty much a given. IOW,
everyone already knows this.
CD/DVD technology will eventually be superceded; this doesn't mean
they are not to be used, but instead means the data will need to be
transferred eventually.
Hard drives make a wonderful medium for storage of data that's to be
transferred to more permanent media, like CD/DVD. But that HD will
fail, eventually.

--
Bill Funk
Change "g" to "a"
Anonymous
December 27, 2004 9:50:23 PM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (27 Dec 2004 10:13:22 -0800) it happened "BrianEWilliams"
<sorry_no_email@yahoo.com> wrote in
<1104171202.464669.79830@z14g2000cwz.googlegroups.com>:

>Many of my older CD-R's are partially unreadable now, and a new DVD-R
>is also partially unreadable.
Specify 'older'.
I have CD-R here that are 4 years old and 100% data verified.

> As a result, I have little faith in this
>type of media for critical storage, and I am leaning towards buying
>lots of hard drive storage so that I can keep a copy on optical disk as
>well as magnetic disk. My intuition is that a quality hard drive that
>is only used occasionally will probably outlast me.
Drop the disk drive (I did once) and forever say goodbye to your data.
And how much can a 400 GB drive store? 85 DVD? I have more then that.
Not even to mention if you have parallel drive now, in 10 years nothing will
accept that, all serial, and probably the next thing after serial ATA,
who knows.
So then keep the whole PC as backup?
maybe your monitor will be incompatible then.. Digital encrypted connection.
Maybe best is to test 'read' on those DVDs / CDRs every year or so, if you
get data errors - lots of retries - copy to new disk...

Altogether I am very satisfied with my DVDs / CDRs, there have been problems,
wit defective disks, look at the layers, if you see spots or sort of cloudy
areas, back them up (some of my old TDK CDR have that, some went back for
that).
Use good quality products.
Keep the backups in separate boxes, good humidity, temperature, out of
sunlight, do not bend of crack or use force on these, do not write with
dubious pens on CDR so the layer does not get damaged.. etc..
Common sense will go a long way.
AND KEEP A DATA BASE this is 'self discipline', and if you get more and more
the only way to ever find anything back.
Every time you burn something update the database immediately, and keep at least
2 backups of that database on different disks / memory stick, wherever.

If all else fails, tar + zip all your work, get one of those 'unlimited' free
email accounts, encrypt with some algo and key only you know, and stuff it on
their server.
LOL
JP
Anonymous
December 27, 2004 11:58:11 PM

Archived from groups: rec.video.desktop (More info?)

Let me ask you this. Is this a problem that has just started recently? Maybe
over just the past month or two? Did you by any chance install Windows XP
SP2? I began to have problems reading discs after installing SP2. In fact,
several programs that once installed on XP with SP1 stopped installation all
together. I had multi-session CD's written with Nero that would not continue
using the multi-session in the exact version of Nero they were written with.
When trying to do a simple format of a floppy disc I received a message the
disc was write protected...and it wasn't!!

If this has nothing to do with the install of SP2 I apologize for the
descriptions.


"BrianEWilliams" <sorry_no_email@yahoo.com> wrote in message
news:1104171202.464669.79830@z14g2000cwz.googlegroups.com...
> Many of my older CD-R's are partially unreadable now, and a new DVD-R
> is also partially unreadable. As a result, I have little faith in this
> type of media for critical storage, and I am leaning towards buying
> lots of hard drive storage so that I can keep a copy on optical disk as
> well as magnetic disk. My intuition is that a quality hard drive that
> is only used occasionally will probably outlast me.
>
Anonymous
December 28, 2004 2:31:17 PM

Archived from groups: rec.video.desktop (More info?)

> Many of my older CD-R's are partially unreadable now, and a new DVD-R
> is also partially unreadable. As a result, I have little faith in this

1) Use a quality disc. Here, Mitsui Gold CD-R for CD-Rs; Maxell
(made in Japan only labeled) DVD-Rs.

2) Use a quality burner. Liteon for CD-Rs; Pioneer/Plextor for DVDs.

3) Verify after writes, both CD-R and DVDRs.

4) Verify PI/PO error rates after writes (DVDr; use
Plextor/Liteon/etc. drives that have this feature).

5) Store in cool, closed environment. (eg. simplest? buy a plastic
storage box, throw the discs in, and close - then stick it somewhere
away from light and heat, like under a bed or closet)

6) Make two copies, the second to any other brand/make media.

---

That said, all of my Mitsui Gold CD-R discs from 10 years ago still
read just fine. Can't say anything about DVDs since they're too new to
tell, but DVD disc rot, edge corrosion, etc. are commonly seen in many
DVD recordable discs even today (poorly made discs). Best bet is to use
a quality disc such as those noted above, and make two copies, and store
in a good area.

Between the two, I'd say CD-Rs can easily go 20-30 years in storage,
but DVDs? who knows? too new to tell.
Anonymous
December 28, 2004 3:23:21 PM

Archived from groups: rec.video.desktop (More info?)

John wrote:

> It seems odd that when CD's were first being
> promoted that the music industry claimed you
> did not need to worry about scratching them
> since it was a digital media and any scratch
> would be trivial when it came to playback.
> They showed them being tossed about like
> frisbies, used as drink coasters and then
> playing perfectly. Maybe they used better
> plastic back then.

They had a small amount of material from that
flying saucer from "The Day the Earth Stood
Still." It's all gone now. Most of it went into
PaperMate pens and Timex watches in the 50s.
The lion's share of the remainder was used
in DeLoreans.
Anonymous
December 29, 2004 5:54:30 PM

Archived from groups: rec.video.desktop (More info?)

On Tue, 28 Dec 2004 11:31:17 -0800, David Chien <chiendh@uci.edu>
wrote:

>> Many of my older CD-R's are partially unreadable now, and a new DVD-R
>> is also partially unreadable. As a result, I have little faith in this
>
> 1) Use a quality disc. Here, Mitsui Gold CD-R for CD-Rs; Maxell
>(made in Japan only labeled) DVD-Rs.

I'm gonna jump in here with an observation.
I'm in two User Groups; I often se epeople complain about making
'coasters', who then explain that buying a different brand of disc
solved the problem.
Probing a little, I find that these people have, as a rule, bought
'bargain bin' burners. They shopped by price.
It's been my observation (and experience) that the better burners will
accept the cheapest discs as well as the high priced ones.
I use a TDK 4800K; it will burn even the GQ discs from Fry's without
any problem.
My DVD burner is a Sony 510a; it will burn the cheapest DVDs I can
find.
I have "El Cheapo" CD-Rs from many years ago, they still work fine,
because I didn't scrimp on the burner. Others, who did, are finding
discs from only 2 or 3 years ago that are no longer readable.

This is, IMO, far more important than the "right" discs.

--
Bill Funk
Change "g" to "a"
Anonymous
December 29, 2004 7:28:04 PM

Archived from groups: rec.video.desktop (More info?)

>
> 6) Make two copies, the second to any other brand/make media.
>
> ---
>
> That said, all of my Mitsui Gold CD-R discs from 10 years ago still
> read just fine. Can't say anything about DVDs since they're too new to
> tell, but DVD disc rot, edge corrosion, etc. are commonly seen in many
> DVD recordable discs even today (poorly made discs). Best bet is to use
> a quality disc such as those noted above, and make two copies, and store
> in a good area.
>
> Between the two, I'd say CD-Rs can easily go 20-30 years in storage,
> but DVDs? who knows? too new to tell.
>
>

If the stuff is that important you can just recopy them every 6 years
and you won't have anyhing to worry about.
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia
http://www.ramsays-online.com
Anonymous
December 30, 2004 2:31:47 AM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (Wed, 29 Dec 2004 14:54:30 -0700) it happened Big Bill
<bill@pipping.com> wrote in <lg96t05ov88c7pi1d328c381dblbiala06@4ax.com>:> 1) Use a quality disc. Here, Mitsui Gold CD-R for CD-Rs; Maxell
>>(made in Japan only labeled) DVD-Rs.
>
>I'm gonna jump in here with an observation.
OK, this is all as scientific as the occasional weather observation.
The point is you may all be right.
But before 'generalizing' here is a real scientific research article
by NIST (A US national institute, and you bet they care about their data):
http://nvl.nist.gov/pub/nistpubs/jres/current.htm

Look for the pdf that says:
Stability Comparison of Recordable Optical Discs--A Study of Error Rates in
Harsh Conditions (PDF File) 654 kb
Oliver Slattery, Richang Lu, Jian Zheng, Fred Byers, and Xiao Tang

In short thr conclusion is really interesting, and confirms what I
wrote about here some years ago, that manufacturers (was my experience with
TDK) change layer formula frequently.
So, and their little graphs are very interesting.
I dunno about MS Windows but in Linux VCD imager reports the layer material.

JP
Anonymous
December 30, 2004 2:36:51 AM

Archived from groups: rec.video.desktop (More info?)

I wrote:
>I dunno about MS Windows but in Linux VCD imager reports the layer material.
Sorry correction, not vcdimager, but cdrecord of cause.
JP
Anonymous
December 31, 2004 9:55:36 AM

Archived from groups: rec.video.desktop (More info?)

Thanks for all the replies. Another poster asked if I was using XP
SP2, and I am not. The failure that triggered the post was a recent
DVD-R I burned with the backup of some work project. Recent is about 4
months old. Much of it is unreadable now. I don't know for sure if it
was ever readable.

My problem with optical disk is that it seems like you only find out
that a disk is bad after it's too late. Hard drives often give notice
of failure, and if they are kept in a drawer, I think they would last
decades at least.

Another attraction of hard disk drives is simply my excellent
experience with them. If they are kept cool and not physically abused,
they seem to provide very reliable storage. Being higher value
products, they are tested more thoroughly than optical disks, and once
they have been reliable for the initial burn-in, chances are they will
last some time.

I *KNOW* some people's experiences are different, but I am also not
looking to store life-critical information, I just would like a
convenient way to backup things that will be reasonably reliable.
Copying to hard drive is MUCH easier. Restoring from hard drive is
MUCH easier. I have absolutely no worries that my current hard drives
will be incompatible with all future computer systems. The reasons
include my multiple current systems, my firewire enclosure box, and the
likelihood of millions of boxes being available for $50 each in the
future.

Maybe it is less secure than backing up to multiple optical disks from
different manufacturers and storing them in an archival grade
environment, but it is still an idea that I like because backing up
video files to optical disk is simply a pain.
Anonymous
December 31, 2004 6:11:28 PM

Archived from groups: rec.video.desktop (More info?)

>
> I *KNOW* some people's experiences are different, but I am also not
> looking to store life-critical information, I just would like a
> convenient way to backup things that will be reasonably reliable.
> Copying to hard drive is MUCH easier. Restoring from hard drive is
> MUCH easier. I have absolutely no worries that my current hard drives
> will be incompatible with all future computer systems. The reasons
> include my multiple current systems, my firewire enclosure box, and the
> likelihood of millions of boxes being available for $50 each in the
> future.
>
> Maybe it is less secure than backing up to multiple optical disks from
> different manufacturers and storing them in an archival grade
> environment, but it is still an idea that I like because backing up
> video files to optical disk is simply a pain.
>
>
>

Aren't you worried about a nuclear blast erasing your magnetic storage?
:)  Someone actually stated that as a reason for not using removable
hard drives for archiving when we were talking about it on a web board,
I think it was vcdhelp.com. I'm guessing he was american. I figure my
hard drives will be the least of my worries on that day.
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia
http://www.ramsays-online.com
Anonymous
December 31, 2004 8:53:20 PM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (31 Dec 2004 06:55:36 -0800) it happened "BrianEWilliams"
<sorry_no_email@yahoo.com> wrote in
<1104504936.142216.151630@z14g2000cwz.googlegroups.com>:


>Maybe it is less secure than backing up to multiple optical disks from
>different manufacturers and storing them in an archival grade
>environment, but it is still an idea that I like because backing up
>video files to optical disk is simply a pain.

Not with good software, and you can look at it too!
Drop 1 DVD and lose at the most some sectors of data.
Drop your HD and now aht do you do?
Want to risk a year of work on that?
For sure, if that is what you want, have fun.

DVD backup is actually the simplest thing in Linux, just type the command.
Same for verification (one should).
And while it is burning you can do other things too.
On the fly, without intermediate files.
tar -zc --to-stdout mydir/* | growisofs -Z /dev/dvd=/dev/fd/

And to get it all back:
tar -zxvf /dev/dvd

You'd better do that in an empty dir.

So whats difficult?

Of cause one should run a verify on the DVD against the tgz...
So, what I am saying is: NO MATTER WHAT THE FORMAT IS, write it as a dvdimage

I often do:
growisofs -Z /dev/dvd=mymovie.mpg

So, this gives me the full 4.7 Gb for the movie.
Does not matter what format it is in, but of cause 1 per DVD.

and then play with
mplayer /dev/dvd

or restore with
cat /dev/dvd > mymovie.mpg (write on disk what it was).
Who needs authoring, VOBS, diskspace....

This is the most efficient way to do things, unfortunatly (most) players
will not play an image....
If I desgined one it would be the fist thing to add (and little menu
to select file type).

No optical disks (CDR DVD ) is fun.
JP
Anonymous
December 31, 2004 9:03:53 PM

Archived from groups: rec.video.desktop (More info?)

>DVD backup is actually the simplest thing in Linux, just type the command.
>Same for verification (one should).
>And while it is burning you can do other things too.
>On the fly, without intermediate files.

Correction:
>tar -zc --to-stdout mydir/* | growisofs -Z /dev/dvd=/dev/fd/

That should of cause be:
tar -zc --to-stdout mydir/* | growisofs -Z /dev/dvd=/dev/fd/0

>And to get it all back:
>tar -zxvf /dev/dvd
JP
Anonymous
January 4, 2005 9:15:45 PM

Archived from groups: rec.video.desktop (More info?)

> by NIST (A US national institute, and you bet they care about their data):
> http://nvl.nist.gov/pub/nistpubs/jres/current.htm
>
> Look for the pdf that says:
> Stability Comparison of Recordable Optical Discs--A Study of Error Rates in
> Harsh Conditions (PDF File) 654 kb

The P.cyanine + silver/gold combo they noted is basically anything
with a silver or gold reflective layer + light-green/almost silver bottom.

The azo dye discs refer only to the Verbatim/Mitsubishi discs with
dark blue bottoms - they're the only ones that make azo discs.

cyanine discs are anything with a light-blue (rather than light-green
above) tint on the bottom due to the different dye.
Anonymous
January 4, 2005 9:21:28 PM

Archived from groups: rec.video.desktop (More info?)

> that a disk is bad after it's too late. Hard drives often give notice
> of failure, and if they are kept in a drawer, I think they would last
> decades at least.
>
> Another attraction of hard disk drives is simply my excellent

My general experience - HDs fail faster than any optical CD-R media
in existence, and I wouldn't bother with long term storage on one.
Magnetic media, failing motors, etc. all equal faster failure rates.
3-5 years max on most HDs is my take on them.

CD-Rs I've had from 10+ years ago still remain readable and useable -
no HD from way back then has survived.

(Note: today's increased reliability in some HDs may let you store
data on modern HDs longer; but don't believe it - look at all of the
failing Maxtor's/WD's/IBM's as noted in www.fatwallet.com/forums/ and
elsewhere -- seems some of the BIG capacity HDs today aren't made to
last...)
Anonymous
January 5, 2005 5:10:25 PM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (Tue, 04 Jan 2005 18:15:45 -0800) it happened David Chien
<chiendh@uci.edu> wrote in <crfike$q0d$1@news.service.uci.edu>:

>> by NIST (A US national institute, and you bet they care about their data):
>> http://nvl.nist.gov/pub/nistpubs/jres/current.htm
>>
>> Look for the pdf that says:
>> Stability Comparison of Recordable Optical Discs--A Study of Error Rates in
>> Harsh Conditions (PDF File) 654 kb
>
> The P.cyanine + silver/gold combo they noted is basically anything
>with a silver or gold reflective layer + light-green/almost silver bottom.
>
> The azo dye discs refer only to the Verbatim/Mitsubishi discs with
>dark blue bottoms - they're the only ones that make azo discs.
Strange you mention that, I just got 50 Ritec 4x DVD+R for 20 Euro, and I also
have those Verbatim dark blue (www.opus.de).
The Ritek looks much the same ah, I just took one of each, held them next to
each other, and exactly the same deep blue.
Thought it was a good deal....
I have now burned 3 of the Ritek, and full verify, 2 all the way up to
4700000000 bytes, 100% OK.
Time will tell, I am happy with this price, use this for archive, Verbatim is OK
too.
JP
Anonymous
January 5, 2005 5:24:36 PM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (Tue, 04 Jan 2005 18:21:28 -0800) it happened David Chien
<chiendh@uci.edu> wrote in <crfiv6$qcp$1@news.service.uci.edu>:

(Note: today's increased reliability in some HDs may let you store
>data on modern HDs longer; but don't believe it - look at all of the
>failing Maxtor's/WD's/IBM's as noted in www.fatwallet.com/forums/ and
>elsewhere -- seems some of the BIG capacity HDs today aren't made to
>last...)
I have 2 40 GB seagates here in the server that have been on 24/7 since
august 2001, and still going strong, they are being USED.

My Maxtors, Western Digital, all died within a year and a half or so.
So I only want Seagate now...
But backups and archive go to DVD!
JP
Anonymous
January 5, 2005 5:30:52 PM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (Wed, 05 Jan 2005 14:10:25 GMT) it happened Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote in
<1104934231.48f2909788089659aa44dd159ecaa471@teranews>:
I just got 50 Ritec 4x DVD+R for 20 Euro, and I also
>have those Verbatim dark blue (www.opus.de).
Correction, www.opus.nl, for the germans it is www.opusshop.de. opus.de
was obviously already in use by someone else.
JP
Anonymous
January 5, 2005 6:23:00 PM

Archived from groups: rec.video.desktop (More info?)

In article <1104935082.c29b9f583d0f520dbf2ea7decc99785f@teranews>,
pNaonStpealmtje@yahoo.com says...
> I have 2 40 GB seagates here in the server that have been on 24/7 since
> august 2001, and still going strong, they are being USED.
>
> My Maxtors, Western Digital, all died within a year and a half or so.
> So I only want Seagate now...
> But backups and archive go to DVD!
> JP
>
>

They don't make em like they used to. I would have a really hard time
heating my office with two 40 GB drives, but my two 120 GB 7200 rpm
drives, no problem :) 
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia
http://www.ramsays-online.com
Anonymous
January 6, 2005 9:39:53 AM

Archived from groups: rec.video.desktop (More info?)

Courious but the only new drive that I had to send back was a Seagate.
Must admitt they did a great job replacing it.

On Wed, 05 Jan 2005 15:23:00 GMT, Chris Phillipo
<cphillipo@ramsays-online.com> wrote:

>In article <1104935082.c29b9f583d0f520dbf2ea7decc99785f@teranews>,
>pNaonStpealmtje@yahoo.com says...
>> I have 2 40 GB seagates here in the server that have been on 24/7 since
>> august 2001, and still going strong, they are being USED.
>>
>> My Maxtors, Western Digital, all died within a year and a half or so.
>> So I only want Seagate now...
>> But backups and archive go to DVD!
>> JP
>>
>>
>
>They don't make em like they used to. I would have a really hard time
>heating my office with two 40 GB drives, but my two 120 GB 7200 rpm
>drives, no problem :) 
Anonymous
January 7, 2005 2:01:16 PM

Archived from groups: rec.video.desktop (More info?)

>> The P.cyanine + silver/gold combo they noted is basically anything
>>with a silver or gold reflective layer + light-green/almost silver bottom.
>>
>> The azo dye discs refer only to the Verbatim/Mitsubishi discs with
>>dark blue bottoms - they're the only ones that make azo discs.
>
> Strange you mention that, I just got 50 Ritec 4x DVD+R for 20 Euro, and I also
> have those Verbatim dark blue (www.opus.de).
> The Ritek looks much the same ah, I just took one of each, held them next to
> each other, and exactly the same deep blue.

Sorry, didn't know you didn't read the article itself (which stated
that they knew the dye composition of CD-R discs; but no idea what's in
DVD discs).

Here, I was referencing the table of CD-R samples which listed the
dye types for each sample disc, and was letting everyone know which dye
type corresponded to which kinds of CD-Rs you can buy today (NOT DVDs,
which you're looking at based on the byte value you stated).
Anonymous
January 8, 2005 12:15:55 AM

Archived from groups: rec.video.desktop (More info?)

On a sunny day (Fri, 07 Jan 2005 11:01:16 -0800) it happened David Chien
<chiendh@uci.edu> wrote in <crmm9l$7mn$1@news.service.uci.edu>:

>
>
>>> The P.cyanine + silver/gold combo they noted is basically anything
>>>with a silver or gold reflective layer + light-green/almost silver bottom.
>>>
>>> The azo dye discs refer only to the Verbatim/Mitsubishi discs with
>>>dark blue bottoms - they're the only ones that make azo discs.
>>
>> Strange you mention that, I just got 50 Ritec 4x DVD+R for 20 Euro, and I also
>> have those Verbatim dark blue (www.opus.de).
>> The Ritek looks much the same ah, I just took one of each, held them next to
>> each other, and exactly the same deep blue.
>
> Sorry, didn't know you didn't read the article itself (which stated
>that they knew the dye composition of CD-R discs; but no idea what's in
>DVD discs).
>
> Here, I was referencing the table of CD-R samples which listed the
>dye types for each sample disc, and was letting everyone know which dye
>type corresponded to which kinds of CD-Rs you can buy today (NOT DVDs,
>which you're looking at based on the byte value you stated).
OK,

http://www.verbatim-europe.com/index/product_view.php?m...
will tell you that Verbatim DVD has:

* Advanced AZO / Metal AZO Recording Layer
* 8.5GB / 4.7 GB capacity
* Highest level of recording stability
* Superior archival life
* For Video (CLV) and Data (CAV) applications
* Available in Jewel Case, Spindles or Video Tall box

That NIST did not bother to look up the source is no concern of mine.
!