Re: [Dvdrtools-users] DVD+R/+RW support

[Bryan J . Smith]

Volker Kuhlmann wrote:
> From my point of view (home + small business user) I have to disagree. A
> quick count of local shops' online catalogs gives:
> shop A: 12 different DVD burners listed, not one with -RAM

Are you certain?
9 times out of 10, a consumer drive that also does DVD-RAM is *not* 
mentioned as DVD-RAM.
Also, most of the Type 1 DVD-RAM drives are listed under a non-DVD 
section.

If they sell LG GSA-4000 series, they do DVD-RAM.
9 out of 10 adds don't even mention it.

> shop B: has 2 or 3 iomega DVD-RAM capable burners
> It's possible they didn't add -RAM to their feature lists, but neither
> sells -RAM media. It's clear that DVD-RAM essentially doesn't feature.

DVD-RAM discs are dold by all media suppliers and CompUSA.
You don't find Macs and Mac software at Best Buy and many of these 
catalogs either.

> Perhaps in the highly professional area it's different, but even there I
> doubt volumes are high.

Again, poor assumption.
DVD-RAM drives sold in such quantity their first year (1997) that the 
price dropped from over $1,500 to under $500.
By the time the first DVD-R/RW drives were released, the 3rd Gen 
DVD-RAM/R drives were still cheaper due to volume.

Sure, now that DVD-R/RW and DVD+R/RW dominate, I'm sure they are less 
popular in comparison.
But the MultiDVD drives that do *all*5* types are still more common than 
you think.

DVD-RAM is *not* a commodity consumer format, and it is *never* marketed 
as such.
But you were talking backup, and DVD-RAM is the king, and *no*one*, not 
even Sony/Philips themselves, can debate the reliability of DVD-RAM for 
backup versus DVD-RW and DVD+RW.

> Out of interest I might ring a few more shops next week though.

Ask them if they carry an LG GSA-4000 series or Matsushita or Panasonic 
LF-500 series or newer.
If so, it's DVD-RAM.

> Come on, that says nothing about its popularity, performance, or
> expected time of "being around".

Do you know the first thing about optical archiving?
If not, then there's no way I can convey 12 years of experience.
Before you even bought your first 650MB CD-R (or CD-RW for that matter), 
I was archiving to 1.3-2.6GB MO discs.
All DVD-RAM did was finally produce a *standard* for 2.6-9.4GB MO, with 
radically improved reliability.

CD-RW, DVD-RW and DVD+RW implement *cheap*, consumer compatible MO.
It is *not* MO designed for long-term back-up.
When consumers have forgotten about DVD-RW and DVD+RW, possibly moved 
onto BlueRay or something else, there will be 2 older discs still in 
used.

DVD-R(G) WORM and DVD-RAM MO.
Not because of marketing to consumers who upgrade every 1-3 years, but 
to archivers who maintain data investments for 15+ years.
DVD-RAM will be around for a long time.

> A prediction. Might well come true...

You don't seem to understand the purpose of DVD-RAM.
DVD-RW and DVD+RW are for short-term consumer use.
DVD-RAM was designed for long-term optical archiving.

Before DVD-RW and DVD+RW, heck before even CD-RW, consumers didn't use 
anything.
But before DVD-RAM and CD-PD, there *were* optical archivers who had 
230, 650 and 1300MB discs per side.
DVD-RAM is a long-term consumer, not a short-term superstore market.

> I don't think the issue of long-term backups are all that simple.
> Longevity studies of optical media seem to have become rather rare 
> since the mid/late 90s.

MO is MO.
It does not compare to ROM or WORM, *unless* you enhance it so it 
*breaks* consumer player compatibility.
That is exactly DVD-RAM, which it was heavily criticized for, but it 
sold because optical archivers adopted it 5 years before consumers like 
yourself, because they had already adopted MO 5 years before that.
You seem to be missing this point over and over.

> Verbatim has one online for their DVD+R 4x.

Ignore those, they are comparing brands, not technologies.
MO is a stop-gap solution between magnetic and crystal-laser.
The player compatible MOs are not long-term.
Only enhanced MO like many early proprietary MO designs through the 
DVD-RAM standard are long-term.

Sony/Philips designed DVD+RW for performance and compatibility, not 
longevity.
Ironically, they got the compatibility pretty dead wrong for the first 4 
years until the players just improved in MO compatibility.
Pioneer has been WORM from day 1 with DVD-R(A) and now DVD-R(G) for 
commodity.
They introduced a consumer MO in DVD-RW, but very few use it, because 
DVD-RAM is what you use when you want long-term, non-player MO.

DVD+R MO-hybrid will *never* be as compatible as DVD-R WORM.
This is physical and technical fact.

>  There are
> other solutions too, depending on circumstances. If I have fewer than
> say 20 DVDs, I can easily copy them onto new media every 2-3 years, and
> the somewhat better consumer DVDs (not talking Princo here) will last 
> that long.

You obviously want to talk about media brand names and not actual media 
technology.
Please go educate yourself *outside* of DVD+RW.
And no, most companies don't want to have to maintain a staff to copy 
data every 3 years.
Maybe to test crucial backups, but not to copy.
Especially when standard, consumer MO like DVD-RW or DVD+RW can 
introduce a new error just in the copy!
Long-term archiving means 15+ years shelf-life, and verify-integrated 
reads/writes.

> Do you have any pointers to useful longevity information for any of the
> 5 DVD formats we've been talking here? I'd be very interested.

Read up on MO in general, and the problems with it.
Then read up on Matsushita/Panasonic Phase-Dual, which was first 
introduced in PD-CD and then used for DVD-RAM.
Be warned, 75 percent of "consumer" reviews of think DVD-RAM is a 
cartridge and that's why it's different (that's just the Type 1 
packaging version).

> Oh, I didn't realise that. How does it work? Does the drive handle the
> filesystem? Why do you still need udftools then?

You don't need UDFTools at all.
In the early days (circa 2.2/1998), you needed some userspace support.
DVD-RAM comes pre-formatted UDF, but you can format any fs you like:
# mke2fs /dev/hdc

> You're not talking about the kernel's packet writing? That would work
> with the same steps as above for DVD+RW, and with any filesystem.

Now that DVD+RW support has been added yes, same deal.
DVD-RAM had it back in 1998, before it was expanded to support 
non-PD/DVD-RAM.

> The problem there is that the performance of Linux udf precludes any
> practically usable application (even when ignoring reliability issues).

You seem to keep missing the fact that DVD-RAM isn't so "generic" in MO 
nature.

> Perhaps it works in the case of very few very big files, but as far as 
> eg the files in $HOME are concerned, it's not usable. Well that was my
> result of an initial speed test on kernel 2.4.~18 anyway. And it wasn't
> that easy, documentation was and is non-existant.

With DVD+RW or CD-RW, yes.
DVD-RAM is different.

> You lost me here. MO is magneto-optical?, but what are the connotations
> of it, ie what other info is "MO" supposed to communicate to me?

CD+RW, DVD-RW and DVD+RW are simple MO implementations.
DVD+R is a MO hybrid, not WORM like CD-R and DVD-R.
DVD-RAM is a reliability enhanced MO.

> Do you have any pointers, or even a quick summary?

I'm writing a FAQ/HOWTO myself.

> WORM is once-writable here? But there is a DVD+R? I don't understand 
> you here.

Single-grove WORM, that's CD-R and DVD-R.
From the laser's standpoint, it runs from end-point to end-point, like a 
record.

Pie-slice MO does not.  That's why CD-RW MO is recorded in "CD-R WORM 
emulation mode."
And why it doesn't work with many older drives.

DVD+R has the same problem as CD-RW did.

> I'd never use erasable media for long-term, that's why I said "rolling
> backups". They'll be good for a few months. Every so often it goes 
> onto non-erasable media.

But DVD+R is still MO, so just like DVD+RW, you have to worry about 
initial write errors.
The *only* commodity MO that does a verify-after-write is DVD-RAM.

> And DVD+R WORM?

Doesn't exist.
It is an emulated WORM, using a modified DVD+RW MO disc for a cheaper 
price point.

> I don't know anyone who gets a silver disk pressed just for a backup,
> but then I don't work in the military. For the 4 DVD-+R(W) formats (and

No, there are 3 types:
- Pressed ROM, single-groove
- Recorded WORM, single-groove
- Packet Written MO, pie-slice

From the standpoint of laser movement, the first two are physically the 
same.
The latter is completely different.
Or didn't you understand why many CD-ROM drives would read CD-Rs, but 
not CD-RWs?

WORM is physically organized like ROM.
MO is not.



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Bryan J. Smith   mailto:address@hidden
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