Data files & DVD+R vs DVD-R

[Dash040]

Don't know if this is a silly question or not, but.........
Does the DVD+R vs DVD-R format issue apply to data DVDs or is it only a video problem?
I'm wanting to start making backups to DVDs rather than CDs because of the capacity. I bought a dual format DVD burner, but for future compatability I was wanting to know if a DVD ROM can read data files on either type of DVD's (If it's only specified for one format)?
Thanks,
Dash
PS Is there any reliabilty difference between burning data files to DVD vs CD? CDs seem to be pretty reliable these days. Are DVDs just as good?
Thanks again.

[Unbezwingbar]

the issue of + or minus is data and video

since u got a dual format u should be fine

[Unbezwingbar]

oh and I forgot
welcome to ZP

cds and dvds are equally good, the only difference is size. other then that I use both of them

[CompuGeek]

DVD+R versus DVD-R only matters for compatibility with standalone devices like dvd players and xboxes.

DVDs and CDs are both unpredictable because we have no clue what their long term reliability is. Some people have found that many of their CD backups are unreadable after a few years or less.

[Malakai1911]

Why DVD+R(W) is superior to DVD-R(W) (http://www.cdfreaks.com/article/113) (cdfreaks.com)


Defect management and recording quality

Another major advantage of DVD+RW format over DVD-RW (although no drive support it yet) is hardware defect management provided by the DVD+MRW standard (Mt Rainier for DVD+RW). On a DVD+MRW disc, when an error occur during a read or write access to an ECC block, this block is flagged as bad and the drive will not use it any more. Instead, when writing to the disc, data which should have been stored in this bad block are relocated elsewhere ; likewise, when the drive is asked to read these data again, it will fetch them from the new location. These operations are completely transparent for any software (whatever operating system, driver or burning application is used), and while the initiator is requesting consecutive sectors the drive will actually read data from various locations : this new abstraction layer is called Logical to Physical address translation.

As a side note, popular belief is that defect management is only useful when burning new discs (where data which are being written can also be read back, checked and moved to another location if needed), but that it is helpless on discs which get damaged after they have been burned. This is wrong, because when an ECC block is partially damaged and requires several retries to be read (or for instance give too many PI/PO errors), these data can proactively be moved to another clean location on the disc before media wear-out makes them unreadable. Of course, if an ECC block is damaged beyond error correction capabilities, data are definitely lost ; however, only very serious damages can make such a thing happen, as PI/PO correction can handle burst errors larger than 6 mm.

As with formatting, DVD+RW standard enables background verifications, i.e. the disc is checked for defects when the drive is idle. Of course, at any time the user can still read or write to the disc, or eject it from the drive ; background verification would then resume later from where it was stopped. Combining these features together gives a very powerful system which can continuously try to improve the longevity of discs : while the user performs its usual operations, the drive can check in the background the complete surface of the disc and move data from damaged locations to clean areas. Such advanced use of defect management are already described in the DVD+MRW specification, for instance with the Self Monitoring Analysis and Reporting Technology (SMART, a technology inspired from hard discs). Finally, it is important to mention that DVD+MRW provides full read-only compatibility for players which don't understand MRW.

Although DVD-R(W) also support some defect management (Persistent-DM and DRT-DM), it is mainly software based and actions must always be initiated by a specific program. Furthermore, since DVD-RW format lacks the needed structures, address translation has to be performed also by software, and translation tables have to be stored on the user area of the disc according to a higher level specification (for instance in the sparing tables of UDF 2.0). This makes DVD-RW not well suited for simple file storage or image burning, as it requires a complete file system to benefit from defect management. Note also that although DVD-RW cannot use +MRW technology (due to technical differences), DVD+RW can very well use UDF 2.0.

Also a DVD+R(W) disc allows a drive to achieve better writing quality (independently of media quality), because it gives more information to a drive than a DVD-R(W). Indeed, just like with CD-R(W), the best writing settings for a given disc are found at startup during the OPC (Optimum Power Control) algorithm, which use data contained in the pre-pits blocks/ADIP words. And regarding OPC, a DVD+R(W) gives not only more information (e.g. power dependency on wavelength) but also more precise ones (e.g. startup laser power). Moreover, all these information are available for 4 different speed ranges (primary and upper speeds, normal and 4x+ mode), while - format only provides one set of data. This is very important because optimal writing settings are very sensitive to burning speeds. Also the OPC test area of DVD+ is 32768 sectors in total, compared to 7088 sectors for DVD-.

Make of it what you wish. I'm a big "+" supporter. A plusfanboy if you will.

[Ken17625]

I own a duel format writer (8x), but I use +R for blank DVD media.

[CompuGeek]

Malakai1911,

Yes, DVD+MRW is the spiffy new thing, but Dash040 is asking about long term data backup reliability and compatibility.

For data backups it doesn't matter if you use +R or -R. Use a recommended brand name. If you burn with Nero you can use the "verify disc" option to make sure your data is readable.

[Dash040]

Thanks for all the feedback and info everyone!
I almost didn't post the bit about having a dual format burner cause I thought it would confuse my question, and I think I've received two conflicting answers so far.
Basically I want to be able to burn data DVDs that I can read on any computer with a DVD ROM (just like you can with CDs), and I'm not sure if combatibility between formats is an issue with data as it is with video. I just want to be able to burn data on (for example) a DVD-R disk and read it on a friends DVD ROM. Now, will I be able to do that if that DVD ROM only supports the DVD+R format, or does that just apply to video?
I know about changing the bitsetting to get around the format problem when it comes to video, which makes me think that a DVD ROM can read either format, but the question is whether or not it can understand it. Does bitsetting apply to data DVDs?
Thanks again,
Dash

[CompuGeek]

The short answer is you can't burn a DVD and have it work in *every* DVD-ROM drive. Rewriteable media has a lower compatibility than write-once media.

The vast majority of drives should be able to read -R or +R just fine. Some can only read one or the other.