[jaclaz]

A sensible approach (for the future) may be to add anyway some redundancy, like:
http://dvdisaster.net/en/
For recovering CD's, I still use my ancient Pioneer SCSI 1x CD drive (one of those with the caddy tray), in my limited experience I have been able to read more data with it than with any "modern" burner I have handy.

jaclaz

[Multibooter]

jaclaz, on 21 May 2012 - 08:05 AM, said:

A sensible approach (for the future) may be to add anyway some redundancy, like: http://dvdisaster.net/en/

1) dvdisaster
I had tried out dvdisaster v0.70.1 about 5 years ago, but I didn't put it into my tool box. At the time it looked too complicated, burning sets of 2 CDs/DVDs seemed to be easier.

Bad DVD specimen #3 (DVD+RW, see my post #19 above http://www.msfn.org/...post__p__998540 ) would probably have been a challenge for dvdisaster. Only 1 out of 5 good readers was able to read from the DVD, and only 735MB out of 4.1GB burnt originally on the DVD (3 out of 17 files) were readable [wiithout dvdisaster], representing about 20% of the data, i.e. about 80% of the stuff on the DVD was unreadable, when read by file. "... a peak error correction load of 63%, meaning that this degree of damage is handled well by error correction data created with default settings. " http://dvdisaster.net/en/index10.html

"Most drives will not recognize media when the lead-in area before the first sector (near the center hole) is damaged. In such cases, dvdisaster will not be able to recover any content from the media. It is not feasible to enhance the reliability of poor quality media by using dvdisaster. Cheap media can decay within a few days to an extent which will exceed the capabilities of the error correction code. " http://dvdisaster.net/en/qa31.html

dvdisaster cannot archive copy-protected CDs/DVDs http://dvdisaster.ne...qa10.html#media nor "BD-ROM (pressed BDs), DVD-ROM (pressed DVDs), CD-Audio and CD-Video", i.e. dvdisaster does not include tools to convert such plastic media into regular image files.

The Q&A http://dvdisaster.net/en/qa.html contains very good explanations and ideas about how to back up stuff to plastic media and about recovering data from plastic media gone bad.

The comment there "Loss of directory = loss of all files!" was very interesting, so probably the best way to save stuff on plastic media is in the root, without the use of subdirectories. The section "Advantages of image level recovery on optical media" explained to me why reading a bad CD/DVD by sector (i.e. with ImgBurn or UltraISO) produced an iso image with substantially more good files than obtained when reading a bad CD/DVD by file (e.g. Unstoppable Copier or Beyond Compare)

The hints in "Some hints for effectively reading damaged media" http://dvdisaster.net/en/qa36.html are very useful. I can confirm that "Some drives read better while being cold.": one burner was able to recover a lot from a bad CD, which other burners couldn't, just on the first read after power-on. The same burner was not able to repeat this single good read.

dvdisaster, together with the excellent explanations, is a very useful tool to learn about the limitations of plastic media.

2) Considerations for preparing CDs/DVDs that are easier to recover
- creating sets of 2 CDs/DVDs has worked well for me
- rather than saving stuff in a single large file, it may be better to save large files as .rar, split into many small volumes/parts.
If a small part file on DVD1 is bad, there is a good chance that the corresponding small part file on DVD2 is still good, and that a good set of part files can be put together from 2 different CDs/DVDs.
- use a 3% recovery record. Maybe a recovered damaged file, e.g. containing "holes" filled with zeroes when the CD/DVD was read by sector, can be repaired
- I don't use 7-Zip to create .7z archives, I know of no software which can repair damaged 7z archives

Quote

For recovering CD's, I still use my ancient Pioneer SCSI 1x CD drive (one of those with the caddy tray), in my limited experience I have been able to read more data with it than with any "modern" burner I have handy.

I also have several interesting SCSI CD drives. Any suggestion on how to build an external USB box, with a SCSI burner inside?

The attached image displays what I think about the reliability of plastic media. I liked the text on the image: "For installation instructions, see your Quick Start Guide".
The name of the company is coincidental, it's a good Japanese company. The image was produced with Virtual Painter v5.0.

This post has been edited by Multibooter: 24 May 2012 - 02:12 PM

[GrofLuigi]

I had 100% succes rate with recovering bad disks (mostly video DVDs, but also others) with IsoPuzzle. I think it works on the same principle as Dvdisaster, but maybe the accent is on reading with different drives. I use three DVD burners in my computers.

In fact, I was prepared to use Dvdisaster in case IsoPuzzle failed, but it never did.

Just FYI...

GL

[jaclaz]

Just to disambiguate.

The "usage paradigm" of dvdisaster and isopuzzle is completely different.

Quote

Common misunderstandings about dvdisaster:
dvdisaster can not make defective media readable again. Contents of a defective medium can not be recovered without the error correction data.

• dvdisaster is a "preventive" tool that allows you to burn media with redundant info (you will need more bytes used per byte saved).
  
• iso puzzle is a "recover tool" to recover an already (badly burned or deteriorated) media

There is a known Commercial tool (bought a license for it many., many years ago, and at the time, if I remember correctly it was a steep amount of bucks, now at around 40 it sounds to me like a fair price):
http://www.infinadyn...accuburn-r.html
that behaves like dvdisaster (adds redundant data) and possibly has a few more little tricks up it's sleeve (and also has a "companion" recovery app)

And now, for NO apparent reason Millennium (maybe) media:
http://www.forensicf...opic/p=6553813/
http://millenniata.com/


jaclaz

This post has been edited by jaclaz: 25 May 2012 - 11:24 AM

[GrofLuigi]

It shows I never got to really use or study Dvdisaster.

GL

[Multibooter]

jaclaz, on 25 May 2012 - 10:01 AM, said:

And now, for NO apparent reason Millennium (maybe) media:
http://www.forensicf...opic/p=6553813/
http://millenniata.com/

Very interesting link. Since it's a USB device, it may even work with Win98 under nusb.

On the first glance it looks like an expensive Gilette shaver, with about $3.50 each blade
http://www.esystor.c...OD/SYSMD01.html
http://esystor.com/p...uplicators.html

To store 1TB may cost $1000, plus a lot of time to burn 250 DVDs. Another question would be the quality of the M-Ready drive itself. Burners are consumables, and tend to die quite quickly, or the burn quality starts to deteriorate, perhaps after 100 burns. So this could raise the cost per long-lasting DVD to maybe $5 a piece, not counting coasters.

Also: "This machine does not burn any copy protected DVDs or CDs"

[jaclaz]

Multibooter, on 25 May 2012 - 11:50 AM, said:

Also: "This machine does not burn any copy protected DVDs or CDs"

That has nothing to do with the M-disc technology, that is a "duplicator" most of these machine sport that kind of warning (I presume for "legal" reasons ) of course everything depends on the kind of protection the CD/DVD's have, some are simply NOT duplicable, some are, no matter what they say on the home page.

You can get a simple burner, though.
http://www.produplic...c-external.html

jaclaz

[bphlpt]

And LG has a model - WH12LS39 - that supports M-disc, BluRay, Lightscribe, DVD, CD, ie everything I know of - http://www.newegg.co...N82E16827136241 - $79.99 as of today. I have this drive. Nice and quiet as well.

EDIT: The M-Discs are available in 50 packs from Amazon for $136.00 ($2.72 ea) with no tax and free shipping - http://www.amazon.co...k/dp/B005Y4NL5I - So the average costs aren't quite as bad as you feared, Multibooter, only $604/1TB. Combined with dvdisaster I would think the reliability of this approach would be fairly high. The time to make the necessary copies would still be a factor, but the peace of mind might be worth it.

Cheers and Regards

This post has been edited by bphlpt: 26 May 2012 - 08:07 AM

[jaclaz]

bphlpt, on 26 May 2012 - 07:45 AM, said:

And LG has a model - WH12LS39 - that supports M-disc, BluRay, Lightscribe, DVD, CD, ie everything I know of - http://www.newegg.co...N82E16827136241 - $79.99 as of today. I have this drive. Nice and quiet as well.

EDIT: The M-Discs are available in 50 packs from Amazon for $136.00 ($2.72 ea) with no tax and free shipping - http://www.amazon.co...k/dp/B005Y4NL5I - So the average costs aren't quite as bad as you feared, Multibooter, only $604/1TB. Combined with dvdisaster I would think the reliability of this approach would be fairly high. The time to make the necessary copies would still be a factor, but the peace of mind might be worth it.

Cheers and Regards

Good, now that we have if not solved, at least easened the cost aspect , back to the issue.
I personally find that if a DVD survives immersion in liquid nitrogen, it means that it survives immersion in liquid nitrogen (and not necessarily that it will last longer).
The actual Warranty they provide:

Quote

The M-DISC™ has a limited lifetime warranty covering defects in materials and workmanship of the product when the product is used as directed and data is written to the M-DISC™ using an M-READY™ drive. Verification that an M-READY™ LG drive was used to write data may be required. If this product is found to be defective, it will be replaced at no cost to you. Product replacement is your sole remedy under this warranty, This warranty does not apply to normal wear or to damage resulting from abnormal use, misuse, abuse, neglect or accident, or to any incompatibility or poor performance due to the specific computer software or hardware used. Consequential or incidental damages, damage to property, liquidated damages, special damages, and any damages for loss of use or data are excluded. Defective discs will be replaced with a new, functionally equivalent blank disc only.

in NO way endorses - not even INdirectly - the actual durability of a recorded media, so, call me tough as you wish , but I won't trust this particular technology (or the claims they make) based on a single test that may (or may not - independently from the results) be only loosely related to actual time passing.
UNdoubtedly these thingies are "tougher" than conventional media, but are they "tough enough"?

jaclaz

[bphlpt]

jaclaz, on 26 May 2012 - 08:35 AM, said:

... I won't trust this particular technology (or the claims they make) based on a single test that may (or may not - independently from the results) be only loosely related to actual time passing. UNdoubtedly these thingies are "tougher" than conventional media, but are they "tough enough"?

Hey, you brought them up!

Cheers and Regards

This post has been edited by bphlpt: 26 May 2012 - 12:32 PM

[dencorso]

A good test would be getting a 5-pack, burning them, then checking them every half-year for corruption and posting about it.
I just wonder whether there'll be any forums to post and drives capable of reading them, say, 100 years hence, when the test would be starting to get statistically relaiable...

[loblo]

You could also put them 10 minutes in a microwave oven every now and then as to simulate ageing I guess.

[duffy98]

... 10 minutes in the microwave ! .... good to come back here every so often to get some humor ... the icon is perfect ! ... that would be me if I saw my DVDs in the microwave!

... I have never heard of the M-disk, interesting ... probably out of my price range, can't image anyone interested in Windows 98SE and XP software 100 years from now, but there still might be "one old geezer" around somewhere trying to get on the internet with 98SE or XP.

...

This post has been edited by duffy98: 26 May 2012 - 06:47 PM

[jaclaz]

duffy98, on 26 May 2012 - 06:45 PM, said:

the icon is perfect ! ... that would be me if I saw my DVDs in the microwave!

CD/DVD's in the microwave is NO laughing matter.
http://raptor.physic...c.edu/wacky/cd/

Quote

We have attempted to place this largely colloquial area of study on a firmer scientific footing.

but hardly a desired target for scientific studies
I have always thought that most Youtube videos are produced by people with too much free time, but seemingly also respectable scientists have plenty of it.

jaclaz

[duffy98]

jaclaz ... you have the "links" to everything. I would have never guessed that someone actually did a study of putting CDs in the microwave. That icon was not a "laughing" icon ... it was meant to be a "state of shock" look. Anyway, I just bought 400 blank DVDs in the last month and then this discussion started about just how long Cds/DVDs will actually last. I've used various brands through the years but have tried to get Verbatum DVDs when I can at a reasonable price and Amazon dropped the price three times below $22 in late April and early May. They are supposed to have "long term" storage but who can say. I should be set for some time with my supply.

...

[jaclaz]

duffy98, on 27 May 2012 - 06:45 AM, said:

I would have never guessed that someone actually did a study of putting CDs in the microwave.

Hmmm, I doubt you have actually READ carefully the article , item #7 in the references is particularly interesting .

Quote

7. We have found wires bent into this shape useful for temporarily binding papers together. A subsequent publication on this "paper clip device" is forthcoming.

And, JFYI:
http://www.marriedto...sc-research.gif

jaclaz

This post has been edited by jaclaz: 27 May 2012 - 07:27 AM

[duffy98]

Talking about DVDs and some of the better brands ... I am in no way an expert on the best DVDs to buy, just read what others have said or written through the years. I just noticed that Amazon has dropped the price on Verbatim 100 pack DVDs ... this is the Verbatim 95098 product ... Amazon sells another Verbatim DVD also ... Verbatim 97459. I have been trying to find out what the difference is for over an hour on Google and came up with very little information so far ... I have a lot more searching to do, just ran out of time for now. Anyway, I did find an article that isn't too old (Feb 2012) "The 5 Most-Talked-About Optical Discs" and it says this about Verbatium and the two different product numbers.


http://www.pcmech.co...-optical-discs/

... don't know if that link will work but it's correct ...


"Aren’t all Verbatim 100-pack DVD+R spindles the same?" No, they’re not. There are many who very specifically seek out the 95098 spindle, meaning not the 97459 and not the 97460. Many people feel that the 95098 is the best DVD+R recordable Verbatim makes. And no there is no price difference between this particular spindle and others by Verbatim; it just happens to be that people like the 95098 the most.


.... I did just buy the Verbatium 97459 product from Amazon in early May but the DVDs were listed as being made in Thailand and not India ... that seems to be another story and discussion, what country are the various Verbatium DVDs from. Anyway, the DVDs that were around $29 just yesterday are now $21.99 and they are identified as Verbatim 95098. Both products have the "AZO" dye layer.

From the Manufacturer:

The Verbatim AZO recording layer gives our DVD media the competitive advantage-the patented coating delivers protection that lasts generations and provides ultimate resistance to UV light damage. That's why Verbatim's been recognized as the No. 1 Optical Brand in the World*--we consistently provide optical media of the highest quality and compatibility. When drive manufacturers test their products for maximum performance, they use Verbatim--so why wouldn't you?

Mitsubishi Kagaku Media (MKM), Verbatim's parent company in Japan, brings extensive technological research and development to the table. Core technologies, like the AZO recording layer give Verbatim an offering like no other optical manufacturer. This unique and ultra-stable layer strongly resists UV light, withstands high laser and rotation speeds on newer drives and ensures compatibility with current DVD standards.

Verbatim's AZO recording layer not only withstands the extremely high laser and rotation speeds of newer drives, it also maximizes their performance. Verbatim paid particular attention to the durability and light fastness of AZO; tests show that it is more stable than most recording dyes and the least affected by ultraviolet light.

AZO also offers high sensitivity for reliable high-speed recording and high reflectivity to eliminate read errors. The thinness of the recording layer is also critical. The thinner the layer, the higher the sensitivity and power margin; therefore, the better the DVD works for high-speed recording.

What does all this mean for you? Verbatim AZO technology translates into optical products that cost just a little more but are worth the slight difference. They are products you want-offering reliability, high read and write performance, high-quality photos and sound and superior archival protection that lasts.

Features
Warranty - Verbatim manufactures our DVDs to meet our strict quality standards. We stand behind the quality of our products-and our Limited Lifetime Warranty proves it!

Compatibility - our online reviews say it for us; we make DVDs that work--no coasters! Mitsubishi Kagaku Media (MKM), our parent company, has long-standing relationships with drive manufacturers who use our products to test their performance, making Verbatim DVDs the most compatible in the industry.


http://www.amazon.co...m=ATVPDKIKX0DER

.... further down the page it go into detail about the AZO layer ... and comments from other buyers.

--------------------------------------------------------------------------------------------------------------------------

.... as I said earlier, I only know what I read ... I did just order 200 of these Verbatim 95098 DVDs to test them and see how they will burn. I also have the other 97459 product. They are under $22 as I write this but the price could change anytime. Amazon is like that ... sometimes maybe a day or more or just a few hours till the price changes. If anyone has further knowledge of the various Verbatim DVD products ... like to hear about it. As I mentioned earlier, some have posted that Verbatim DVDs made in Thailand or Asia are better than the ones made in India ... but you don't really know, until you get the shipment, where they were made. Hope this might be somewhat helpful ... if the 95098 is the superior product then this is probably a good deal till the price goes back up in the US ... not sure about Amazon prices in other countries ... I sometimes shop and have ordered from other Amazon sites for hard to find DVDs (films) not for sale in the US but I didn't have time to check blank DVDs prices.

...

This post has been edited by duffy98: 28 May 2012 - 08:33 AM

[jaclaz]

duffy98, on 28 May 2012 - 04:46 AM, said:

Talking about DVDs and some of the better brands ...

Just for the record there are reports "here and there" that besides the difference between "good" brands and "bad" brands, there are other two kinds of issues:

• a "same brand" CD/DVD may have been manufactured in a "good" factory and as well in a "bad" factory (there is a way to identify media, see later in this post)
  
• more then the above it seems like a given brand/model of burner will work "better" with a "given brand/make" of media and "worse" with "another brand/make" of media

In other words I have seen more than one report that:
burner model A+media type B=good result
burner model A+media type C=bad result
BUT:
burner model D+media type C=good result
burner model D+media type B=bad result

There is some info "hard encoded" in the media, called "ATIP", (Absolute Time in Pregroove) or ADIP (Address in Pregroove), and quite a few programs capable of reading it, such as:
http://dvd.identifier.cdfreaks.com/

If you analyze this info on a few different media, it will be evident how a same "good" or "bad") factory/manufacturer may make a disc that is sold as either "good" brand A or "bad" brand B, i.e. you can easily find two differently branded disc's (often payed a very different price) having been actually manufactured in the same factory.
It is not at all clear if (as it happens in other industries) there are (within the same factory) "better" batches (which are then marked with "good brand" name) and "bad" batches (which are then marled "no-name" or "cheap brand")

jaclaz

[duffy98]

Ok ... yes jaclaz, just became aware of DVD Identifier in April ... I think it was mentioned by someone posting at Amazon on the Verbatim DVDs as to which were from factories in India and Thailand. I didn't have time to mention DVD Identifier earlier today.

I also didn't have time to get into the Amazon brand DVDs and my experience with them. Last year, they were mostly under $18 all year till late in the year and so far in 2012 the price has been everywhere to as high as $30 / 100 but mostly around $25 ... in Feb (2012) the price dropped below $20 for a short time and I ordered 100 to try them. Most people said they were OK to very good for the price with very few coasters. With the Amazon brand DVDs I bought in Feb ... I found that to be true. I just used them up in the last two weeks and I think I only had one the was bad. In late April the price on the Amazon brand dropped below $22 and I ordered 200 since I had a good experience with the last order. Just started burning them in the last two weeks and my experience with this order is terrible ... just a few days ago, I had five in a row that wouldn't burn or had errors ... Out of about 50 used so far, I'd say about 20 may have been bad or did not finish a complete burn. Just yesterday, I noticed the Amazon brand was below $20 ... still is today when I discovered the Verbatim brand on sale. However, I noticed there were several customer postings over the last seven days complaining of bad burns and many coasters. Perhaps this batch of Amazon DVDs have a problem. I will not buy them anymore myself ... will use the Verbatim brand for now. Also, as someone posted about the Amazon brand ... the DVD is a little "thicker" than most other DVDs, so it might not work in all DVD players or need to be pushed down harder on a spindle to get it to set correctly. I found this to be true, they are somewhat thicker ... I noticed that Verbatim says this about their DVDs: AZO also offers high sensitivity for reliable high-speed recording and high reflectivity to eliminate read errors. The thinness of the recording layer is also critical. The thinner the layer, the higher the sensitivity and power margin; therefore, the better the DVD works for high-speed recording.

... so the Amazon brand DVDs are also on sale but for a little more in price, the Verbatims might be the better deal, if you need some DVDs.

...

[Multibooter]

jaclaz, on 28 May 2012 - 05:43 AM, said:

It is not at all clear if (as it happens in other industries) there are (within the same factory) "better" batches (which are then marked with "good brand" name) and "bad" batches (which are then marled "no-name" or "cheap brand")

I would speculate that the good batches go to Europe and the inferior batches go to the USA, where one can usually return bought items within 14 days, but not after that; to get a longer warranty, you have to buy an additional service contract. So writable DVD media sold in the US should work reliably for at least 14 days