I've been using recordable CDs to archive data for a long time. My experience has been that they're very robust. I've burnt hundreds of them (all good brands like Verbatim, Fujifilm and Sony) and have never had a problem with one (unlike floppies, hard drives, Jaz drives and other storage systems). The oldest CDs are now ten years old.
Thing is, I could really do with more capacity on a single disc. But I need the long lifetime. Does anyone know if recordable DVDs are as durable? DVDs are the only alternative for me, because I already have the DVD recorder, and I'm feeling cheap. Can someone give me an authoritative answer, or point me in the direction of a book or website that does?
On May 13, 8:08=A0pm, Christopher Tidy . Can someone give me an
I have copied music CD's so as to have copies in more than one place. And mostly used CD's manufactured by Ritek ( sold by Fry's as GQ). My results have not been all that good. No big deal to me as I just make another copy from the original.
But do a search on Taiyo Yuden. From what I have read at various website they are one of the best blank manufacturers.
I can't answer that with any authority other than I've been using DVDs for backup for 5 or 6 years. Then seem to be holding up ok.
Having said that, it's important to note the difference in construction between CDs and DVDs. THey may look the same, but they aren't. Not by a country mile.
DVDs are two layers laminated together while CDs are a single piece of plastic,
here is a quicky...
formatting link
the tracks don't "spiral")
Quick... How many grooves are there on an old fashioned LP record?
I burn DL dual layers in the living room. I don't press them. It is one color inside to outside - I want to say a blue and then red. The other is the other color. Not all dvd players can play them. Not all dvd writers can read or write them. They are expensive and special. These are dual logical layers.
Production ones are dual often and are pressed that way. Production is the dual physical layers.
One thing to keep in mind about CD's and CDR's is that the actual data layer, either dye or pressed) is under the label... often only protected by a little paint and/or a coat of lacquer. A small scratch or ding to the label side can spell disaster.
With DVD's (all varieties that I'm aware of anyway) the data layer/s are sandwiched between two layers of Polycarbonate.
As far as writing DVD's goes, the dye layer/s are, and other than size, work about the same CD's. Store them in a cool dark place.
In my personal experience, software that allows multiple burn sessions are often unreliable disappointments, as are 'RW' re-writable type discs.
Back in the 'old days' when all this disc burning jazz started, it was black magic to find blanks that would work with any particular burner... seemingly everything was critical. Burner Mfg and specs, blank dye layer chemistry, rated and actual burn speed/s and of course, outer planet alignment. Lots of coasters were produced.
Then, and for all I know now, there were only a hand full of companies actually producing blank CD's and DVD's, even though they sold under many brand names. Many considered those actually made by Taiyo Yuden to be by far the best. I've never seen a blank that actually sports TY's name or logo.
formatting link
But as time goes on, it seems like pretty much all blanks work well now.
I used to have a ton of links related to burning... I went through burn bookmark folder, and included the 7 links that still work... not that many, but enough to keep you busy for a while. Note most of these are long in the tooth. See below.
To dispose of discs containing sensitive data, chop them up with sheet metal shears. Be careful if you decide to break them... they can really cut you. In that case, put them in a thickish section of newspaper or a magazine, break them, then just toss the whole mess.
OT: I used to back up my computer to CDR's, then later DVD+R's, but since USB flash drives matured, I've used them. I have two... one that fits nicely in my cell phone case, and another I keep over at a well trusted neighbors house... I update them both every month to 6 weeks. (Yea, I know about portable hard drives, but I'm stuck in my ways, and they work well for me.)
DVD-R and DVD+R discs can be either single or double-sided. A single-sided (SS) disc is composed of a recording side and a dummy side while a double-sided (DS) disc consists of two recording sides. The recording side of a DVD-R and DVD+R disc is a sandwich of a number of layers. First comes a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside diameter of the disc. A DVD-R disc additionally includes pits and lands on the areas between the coils of the groove (land pre-pits). Added to this substrate is an organic dye recording layer (azo, cyanine, dipyrromethene or others) followed by a metal reflective layer (silver, silver alloy, gold). The dummy side of a single-sided disc consists of an additional flat polycarbonate plastic substrate (sometimes with an additional metal layer to obscure the bonding layer from view for aesthetic purposes). An adhesive then bonds two recording sides (for a double-sided) or a recording and dummy side (for a single-sided) together into the final disc. Some single-sided discs are also topped on the dummy side with decorations or additional layers that provide surfaces suitable for labeling by inkjet, thermal transfer or re-transfer printers.
How are DVD-R and DVD+R discs made? The first step in manufacturing a DVD-R or DVD+R disc is to fabricate the polycarbonate plastic substrates (incorporating the spiral groove and land pre-pits) using an injection molding process. The dye is then applied using spin coating and the metal layers by means of DC sputtering. After both sides of the disc are completed they are bonded together using a hot melt, UV cationic or free radical process. Additional decoration or printable layers are typically applied using screen printing methods. A DVD-R (General) disc undergoes a further manufacturing step in which a specialized computer DVD recorder is used to ?prewrite? information in the Control Data Zone of its Lead-in Area to inhibit direct copying of prerecorded DVD-Video discs encrypted with the Content Scrambling System (CSS). Apart from this, and some minor differences in the configuration of the molding stamper used to create the substrates, the process for manufacturing DVD-R and DVD+R discs is virtually identical.
What is the construction of DVD-RW, DVD+RW and DVD-RAM discs? To allow information to not only be written but also re-written many times over, DVD-RW, DVD+RW and DVD-RAM (rewritable) disc construction is more complex than that of DVD-R and DVD+R (recordable). Just like a recordable disc, a rewritable disc can be either single or double-sided. The recording side of a rewritable disc also uses multiple layers beginning with a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside diameter of the disc. A DVD-RW disc additionally includes pits and lands on the areas between the coils of the groove (land pre-pits) and a DVD-RAM disc also inside the groove itself (land and groove). Next comes a dielectric layer (zinc sulfide and silicon dioxide), followed by a phase-change alloy recording layer (either indium, silver, tellurium and antimony or germanium, tellurium and antimony), another dielectric layer and a metal reflective layer (silver, silver alloy, aluminum). Additional layers may also be incorporated above or below the dielectric layers (germanium nitride, silicon carbide, silicon dioxide, silicon nitride, zinc sulfide, antimony telluride and others). The dummy side consists of a flat polycarbonate plastic substrate sometimes with an additional metal layer. An adhesive then bonds the sides together into a single disc. The exterior of the recording side may also be ?hard coated? with a transparent material (indium tin oxide, silicon-based lacquer and others) designed to repel dust and resist fingerprints and scratches. Similar to a barcode in appearance, a DVD-RAM or DVD-RW disc can also contain near its inner diameter an optional Burst Cutting Area (BCA) or Narrow Burst Cutting Area (NBCA) to supply information required to implement Content Protection for Recordable Media (CPRM).
How are DVD-RW, DVD+RW and DVD-RAM discs made? As with DVD-R and DVD+R, producing DVD-RW, DVD+RW or DVD-RAM discs involves using multiple manufacturing stages. The first step is to fabricate the substrates (incorporating the spiral groove, land pre-pits and embossed areas) by injection molding. The dielectric layers, phase-change recording, reflective and any additional layers are applied to the substrate using DC, RF and reactive sputtering. After both sides of the disc are completed they are bonded together using a hot melt, UV cationic or free radical process. Since the sputtering process lays down the phase-change alloy in its amorphous condition a special device using powerful lasers (initializer) returns the recording layer back to its crystalline state. Subsequent recording then results in less reflective (dark) areas being written against a more reflective (bright) background. The Burst Cutting Area (BCA) or Narrow Burst Cutting Area (NBCA) is marked into the disc using the initializer or a dedicated device outfitted with a YAG (yttrium aluminum garnet) laser. Hard coating can be applied to the substrates at different stages in disc manufacturing using a variety of processes such as spin coating, vacuum deposition and screen printing. A DVD-RAM disc can optionally undergo a further manufacturing step in which it is physically formatted by a conventional computer recorder (to detect and map any defective sectors). Apart from some minor differences in the configuration of the molding stamper used to create the substrates the process for manufacturing DVD-RW and DVD+RW discs is virtually identical while DVD-RAM fabrication is more involved.
How does writable DVD and CD disc manufacturing differ? Apart from the thinner substrates and tighter manufacturing tolerances, the most significant difference between writable DVD and CD manufacturing is the need to perfectly bond two DVD halves together to create a disc that is the same thickness as a CD (1.2 mm). It is imperative that the two disc halves have the same long-term mechanical behavior to ensure that the resulting disc maintains its thermo-mechanical stability. This is particularly important for high-speed discs where flatness and uniformity are paramount. Writable DVD disc manufacturing equipment and production steps (with the addition of the bonding stage) closely resemble those used to fabricate their CD counterparts. In fact, many media manufacturers have simply modified their existing CD-R and CD-RW equipment to produce writable DVD discs although it is generally expected to become less feasible to do so (for productivity and product quality demands) as the technology and business evolves.
I'd fully agree with what Eric said about R/W and would add "multi session" disks too. They have never really been reliable for me.
Looking in my back-up book (several 256 disk pocket folders) my backup stack goes back to 1998. All of these are still readable.
I had a problem 5 or 6 years back with a DRIVE that didn't make good disks. (and didn't admit it!)
But once a disc is readable, baring scratches, heat, flex, and "friends" they seem to keep going like the Energizer Bunny.
I think the books are probably not the best storage mechanism for really long term archival. Probably best for that would be individual CD cases. But the books are just too handy to dump and that many CD cases would be expensive and take a lot more storage space.
Taiyo Yuden is the best for CD-R's (TY is the original-spec disk performance standard, and the longest life)
MAM-A gold disks are the best DVD's for long life
Very likely you gotta order them both online.
MAM-A also makes "gold" CD-R's that give a long life after burning also, but there is some debate as to how effective they are, since they do not meed the original CR-R specs.
And keep in mind,,,, most burned disks get ruined from physical damage, not corruption due to the recordable media itself.
Also another option to consider: a typical hard drive can safely store data 15-20+ years, if it is completely disconnected from all power sources and kept at a moderate temperature.
Erik wrote in news:spam-D0157C.22190413052011 @news.dslextreme.com:
I would NEVER use USB flash for backup. I've seen way too many USB drives suddenly go bad. In my experience, they are only slightly better than floppies. They are probably better now than they once were, but I only use them to move data around. If data is worth backing up, it's worth backing up onto something reliable.
On the original topic, for CD's I always used Mitsui gold disks. They are now sold under the name "MAM-A". They were touted as the best for many years, and I've never had a problem. They also make DVD's, and are considered by conservationists & archivists as the most stable disks around.
Thanks for all the advice. I guess last night I was thinking that the dyes were probably the same, but that for a DVD, the smaller marks burnt into the dye and the closer tracks might have an influence on durability. Looks like there isn't any evidence of this, so having read around, I think I'll go with Verbatim AZO DVD+R. They might not be the ultimate, but I can get them easily, and that means I'm more likely to actually make the back up. They're going to be in a cold and dark place anyway. I just want a copy in a different building in case of fire.
Humidity irrc has a large effect on CD life. I seem to remember reading about cd rot a long time ago. I'm not sure that I have experienced it when reading long term cd's since it is possible that the recorder a decade plus might not have been all that good. I remember the days of 2x SCSI burners.
Burning two copies, doing a hash of the contents and filing that away then periodically scanning the disk to see if you can get the same hash might be a way to tell if data loss is in progress. With two copies, you might be able to get your data back.
That hash would need to be on the disk structure and a hash on every file to figure out which one went wrong. The disk hash tells you there is damage.
Of course if we are going that far, maybe using RAR and recovery files spread across disks might be an option.
A few month back I recall seeing a Modern Marvels episode on the Library of Congress. One of the topics covered was their research into the longevity of various media - CD's & DVD's were included. I don't recall the results but I do recall that different base materials were the key and that each mfgr's product varied widely over time as they changed their formulation.
They should be able to give you the last word on your question.
A few month back I recall seeing a Modern Marvels episode on the Library of Congress. One of the topics covered was their research into the longevity of various media - CD's & DVD's were included. I don't recall the results but I do recall that different base materials were the key and that each mfgr's product varied widely over time as they changed their formulation.
They should be able to give you the last word on your question.
formatting link
Art
ps. Reposted due to OE's random stripping of the OT: from the subject line,
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.