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Which discs are larger?


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Coincidentally, it just so happens that I found the answer to your second question purely by tedious experimentation (no googling). The answer is DVD+RW. Evidence is presented below.

Disc name               Disc size       Disc type
Backup 01 - 2009-11-04  4,700,372,992   DVD+RW
Backup 02 - 2009-11-04  4,700,372,992   DVD+RW
Backup 03 - 2009-11-04  4,700,372,992   DVD+RW
Backup 04 - 2009-11-04  4,700,372,992   DVD+RW
Backup 05 - 2009-11-04  4,700,372,992   DVD+RW
Backup 06 - 2009-11-04  4,700,372,992   DVD+RW
Backup 07 - 2009-11-04  4,700,372,992   DVD+RW
Backup 08 - 2009-11-04  4,700,372,992   DVD+RW
Backup 09 - 2009-11-04  4,700,372,992   DVD+RW
Backup 10 - 2009-11-04  4,700,372,992   DVD+RW
Backup 11 - 2009-11-04  4,700,372,992   DVD+RW
Backup 12 - 2009-11-04  4,700,372,992   DVD+RW
Backup 13 - 2009-11-04  4,700,372,992   DVD+RW
Backup 14 - 2009-11-04  4,694,933,504   DVD-RW
Backup 15 - 2009-11-04  4,694,933,504   DVD-RW
Backup 16 - 2009-11-04  4,694,933,504   DVD-RW
Backup 17 - 2009-11-04  4,694,933,504   DVD-RW
Backup 18 - 2009-11-04  4,694,933,504   DVD-RW
Backup 19 - 2009-11-04  4,694,933,504   DVD-RW
Backup 20 - 2009-11-04  4,694,933,504   DVD-RW
Backup 21 - 2009-11-04  4,694,933,504   DVD-RW
Backup 22 - 2009-11-04  4,694,933,504   DVD-RW
Backup 23 - 2009-11-04  4,694,933,504   DVD-RW
Backup 24 - 2009-11-04  4,694,933,504   DVD-RW
Backup 25 - 2009-11-04  4,694,933,504   DVD-RW
Backup 26 - 2009-11-04  4,694,933,504   DVD-RW
Backup 27 - 2009-11-04  3,240,558,592   DVD-RW

What you see is a list of DVD discs containing a 116 GiB (125,379,543,040 byte) backup archive that I split across evenly on 27 DVD discs 12 years ago. The discs I used were Philips I believe (DVD+RW) and from the looks of it I must have run out of those so I switched to Verbatim (DVD-RW). This was a one day job, as you can see by the dates. You will notice that each of the first 13 discs is 4,700,372,992 bytes. Those are the DVD+RW discs. Once I switch over to DVD-RW this number changes to 4,694,933,504 bytes. (The last disc contains only the remaining data that did not fit on the previous discs.)

This was a surprising find, because I had no idea that there was any such difference between DVD-RW and DVD+RW. I take it that this is why the latter has a plus ("+") symbol in the name? I really never knew in what way those "plus" discs were different from regular discs without the plus when they first appeared, I never cared, because they served me equally well as the other, "regular" discs without the plus symbol.

I hope this answers your question. I have not googled this yet (still). I might be wrong. I noticed that there is about 11 MiB unused or free space on each disc. I can't tell if it was exactly the same number for both DVD-RW and DVD+RW. Perhaps this is a reserved space that can't be written to? I don't know. I did not do the splitting myself, a program did that for me, back in the day. But seeing is believing, and I believe DVD+RW will fit more data than a DVD-RW. So it only seems reasonable to assume that the same applies to DVD+R vs. DVD-R.


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I had it in mind that DVD+RW was larger than DVD-RW.


The reason for the + is because the name DVD-R was already taken, being the first DVD WORM recordable media.  When the consortium created their format, they simply chose DVD+R as the name because it made sense to go from minus to plus.


Another advantage of DVD+RW over DVD-RW is the erasure of that media is nearly instantaneous.  There's a lead in time for erasing DVD-RW that takes about a minute.


Another advantage of DVD+RW, I think, is its Writing LeadIn time is shorter than DVD-RW's.


Another is I think DVD-RW only reached 6x max write speed whereas DVD+RW reached 8x.


There is an advantage of using DVD-R over DVD+R when making DVD Video discs.  Since DVD-R is the older format, older DVD players that don't play DVD+R have a better likelihood of playing DVD-R.  DVD-R is more compatible with DVD players because it's an older format.

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DVD-R: Verbatim 16x DVD-R [MCC 03RG20]
Free Sectors: 2,298,496
Free Space: 4,707,319,808 bytes

DVD+R: Verbatim 16x DVD+R [MCC-004-00]
Free Sectors: 2,295,104
Free Space: 4,700,372,992 bytes

DVD-RW: Verbatim 4x DVD-RW [MCC 01RW4X]
Free Sectors: 2,298,496
Free Space: 4,707,319,808 bytes

DVD+RW: Verbatim 4x DVD+RW [MKM-A02-00]
Free Sectors: 2,295,104
Free Space: 4,700,372,992 bytes

For brand comparison...

BEST 16x DVD+R [BeAll000-PG0-00]
Free Sectors: 2,295,104
Free Space: 4,700,372,992 bytes


Edited by Ken852
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Indeed, according to the tests that users have done and posted on this forum, both DVD-R and DVD-RW can hold more data (4,707,319,808 bytes) than DVD+R and DVD+RW (4,700,372,992 bytes).

I referenced a "BEST 16x DVD+R" disc for sake of comparing another brand to Verbatim. This is a very limited sample of course but it indicated that there are no deviations between brands in terms of available storage space. Of course, I remember those kind of tests mainly being done for sake of testing the quality of the discs. I just wanted to see for myself that different brands report same storage space.

But it sounds to me like DVD+RW is the more advanced and preferable choice over DVD-RW when it comes to RW discs. So it would seem wise to get DVD+RW for RW discs (for the advantages listed previously) and DVD-R for R discs (can store more data). Both DVD-R and DVD+R are preferable for data longevity.


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What puzzles me now is why the DVD-RW discs in my backup archive above cut off at 4,694,933,504 bytes, 5 MiB less than that of DVD+RW (4,700,372,992 bytes) when according to the numbers above, DVD-RW discs can fit 6 MiB more than DVD+RW discs (note less). At any rate, I should be able to fit 4,700,372,992 bytes regardless if I use DVD-RW or DVD+RW. The DVD+RW discs are filled to the brim, but not DVD-RW discs. Any explanation for this?


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No, those were written with a PATA drive, the NEC ND-3520A. I currently use a Samsung SH-224DB SATA drive.

I think I used something like 7-Zip or "PeaZip" (same thing, different face) for splitting. So it's a 7-Zip archive.

So I should be able to max out DVD-RW discs at 4,707 ,319,808 bytes? There is no overhead involved or something like that?


Edited by Ken852
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I think UDF 1.02 was used. But that overhead should be equal on both DVD-RW and DVD+RW?

I have not found any specifics about the UDF overhead on DVD discs, but this bit about CD discs is quite interesting:


The so-called UDF overhead that is spread over the entire disc reserves a portion of the data storage space, limiting the useable capacity of CD-RW with e.g. 650 MB of original capacity to around 500 MB.


I am speculating, but it would seem as if UDF is not the ideal choice if you want to max out the capacity of a DVD-RW disc.

This is somewhat related and an interesting question on how to predict the overhead size in UDF formatted discs (or UDF "images" rather):



Edited by Ken852
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