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I am presently saving data on DVD+R was always told to use +R, but never knew why.

  • I am looking into possibly upgrading to BluRay, but can only find -R writable discs:
    What is the difference between +R and -R, and why are there no +RW BluRay discs?
  • I can only find 25GB writable discs, but there are 50GB+ discs, so where do I find those?
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    So what does your research show? Because the Wikipedia article explains in great detail.
    – Daniel B
    Sep 15, 2020 at 10:53
  • Since you're going to be using BluRays for archiving, you may want to get the quad-layer ones (there are 4 layer types: single [25GB], dual [50GB], triple (XL) [100GB], and quad [128GB]). FYI: BluRays have an extremely hard protective layer over their magnetic film medium, so it's vastly more difficult to scratch them (you have to be quite determined to do so)
    – JW0914
    Sep 15, 2020 at 12:45

2 Answers 2

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DVD-R (and DVD-RW), DVD+R (and DVD+RW), DVD-RAM, and BD-R (and BD-RW) are simply four different formats for optical mediums.

The DVD Forum first created the DVD-RAM in 1996 as the re-writable and Random Access version of the DVD-ROM. However, they never marketed it properly, and a DVD-RAM cannot be read by a DVD-ROM drive (although there are hybrid drives). As of June 2019, there are no remaining manufacturers of DVD-RAM media, meaning the format is mostly dead.

Panasonic created the DVD-R as the recordable version and DVD-RW as the re-writable version in 1997, and the DVD Forum accepted this as a standard. DVD-Rs are mostly compatible with DVD-ROMs, so it was possible to develop cheap DVD-ROM drives that could read DVD-Rs (even if they could not write them).

In 2002, a group of manufacturers (driven by Sony) created a competing standard to DVD-R(W) called +R and +RW. (They weren't allowed to call it DVD+R and DVD+RW because they were competing with the official standard of the DVD Forum. The DVD Forum only accepted DVD+R(W) as an alternative to DVD-R(W) in 2006.) This created a "format war" because the two formats were mutually incompatible. While multi-format computer drives quickly became affordable and the norm, DVD Video Recorders even to this day typically only support one format, or are at least functionally restricted.

What is the difference between +R and -R

For a user, there are no differences. There are technical differences between the two formats, and there are some "lessons learned" in the DVD+R, simply by virtue of having 5 years of experience with DVD-R when they designed it.

But the reason why DVD+R was created was purely political. There are no meaningful differences for the end user.

why are there no +R BluRay writable discs?

Such a format war between different manufacturers who developed incompatible competing formats simply never happened in the BluRay Disc Association, so that is why there aren't multiple incompatible competing formats like there are for DVDs.

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  • I am finding BluRay writable drives hard to get in the UK, with some shops only selling 1 (Argos) and other shop selling none at all (PC World). Are they old technology?
    – Rewind
    Sep 15, 2020 at 11:12
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    @Rewind Blu-ray Disc Recordable is simply irrelevant. Too expensive, too inflexible, too late. Flash drives offer superior performance at a very competitive price point.
    – Daniel B
    Sep 15, 2020 at 12:29
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why are there no +R BluRay writable discs?

There is no technical meaning in the "+R" – it's part of a marketing name, and all it means is "like -R but improved". The whole DVD+R is a newer format that was meant to improve over the older DVD-R format (like version 2.0).

Meanwhile, BluRay (BD-R) already had the same improvements incorporated from day 1. But it too had a competing format which was called "HD-DVD", so instead of BD-R vs BD+R you actually had BD-R vs HD-DVD-R.

What is the difference between +R and -R

Here's a Wikipedia article.

Two examples noted there is that the DVD+R format has better error correction, and allows drives to better calibrate their power for the specific disc, which I assume leads to slightly higher quality recording and slightly better resilience to physical damage.

Another difference between DVD-R and DVD+R is that the newer +R format has a different way of defining sector addresses (ADIP), which allows the drive to seek more precisely at high speeds, so writers can easily continue after a buffer underrun, and the discs can fit slightly more data.

(This feature also allows DVD+RW discs to immediately be used for random writing as the drive can seek to and overwrite any sector at any time, whereas DVD-RWs and CD-RWs could only do this after the necessary addresses were written in a lengthy "MRW formatting" step.)

BD-R already uses ADIP from the very beginning. (However, HD DVD-R uses LPP just like DVD-R, so you could perhaps say that BD is the "+" of HD DVD.)

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