[Dvdrtools-users] Re: Newbie question

[Bryan J. Smith]

Quoting Pratul Agarwal <address@hidden>:
> Hi Folks,
> I am planning to get a DVD writer (mainly for backing up data). 
> I just wanted to ask if someone is aware of a list DVD writers 
> which are (un)supported under Linux.
> I have my eyes on:
> SONY DRU500A and Philips DVD RW228 
> (somebody told me that Philips CR writers are flaky, 
> so he thinks DVD writers will be no different).
> Any advice will be HIGHLY appreciated.


FUNDAMENTALS ...


First off, I assume you know there are two ways optical drives can be written 
two:

- "Record" aka "Burn" -- Direct, Sequential, Continous Write from pre-mastered
ISO file
- "Packet Write" aka "Rewrite" -- Random Access, Normal Filesystem Access,
usually with UDF (universal device format) or any supported filesystem (e.g.,
Ext2 on Linux).

So there are two, separate programs that support them.

- CDRTools/DVDRTools -- This allows you to "burn" an ISO file to a CD-R or DVD-R
disk.  It will also allow you to "burn" an ISO file to a rewritable CD-RW or
DVD-RW disk as well (that can be later erased).  This is via the SCSI Generic
(/dev/sg#) device, the "program" has all the "brains."
- Kernel/Filesystem -- This allows you to "packet write" files directly to the
disk in a random-access manner like any other disk.  It uses an underlying
kernel driver and filesystem support -- UDF being ideal.  This is via the SCSI
Disk (/dev/sdX) device, just like any other disk (hence why the "Windows
equivalents," like Adaptec/Roxio "DirectCD" use a drive letter).

[ BTW, _not_ even just UDF filesystem "read" support is included in Windows 95,
NT or 2000 -- you need to download the free Roxio driver so you can read CD-RW
or DVD-RW disks that were "packet written." ]


THE ACTUAL DRIVES ...

There are 3 common drive standards ...


DVD-RAM (DVD Consortium Standard)

- Supporters:  Matushita/Panasonic, Toshiba, Hitachi
- Design:  Long-term optical archiving standard (non-consumer)
- Pros:  Media longevity (100x as many rewrites, 30+ year shelf-life), verify
after write, cartridge option, "universal reader" drive, Gen3 supports same
DVD-R(G) as popular Pioneer/DVD standard
- Cons:  Slow (due to verify), DVD-RAM Rewrite media INcompatibility in players
(designed for archiving, not consumer use)

- RECORD: DVD-R(G) (Gen3 only -- e.g., Panasonic LF-D311)
Linux/DVDRTools does _not_ support this yet.  ProDVD might though.
- REWRITE:  DVD-RAM
The stock Linux kernel has included full DVD-RAM "packet writing" upon DVD-RAM's
initial release (circa 1998)


DVD-RW (DVD Consortium Standard)

- Supporters:  Pioneer, most 3rd parties -- including Sony in new 4x drive
(DVD-R/RW+R+RW combo drive)
- Design:  General consumer usage
- Pros:  Record DVD-R(G) nearly 100% player compatible, Rewrite DVD-RW ~70%
player compatible, Gen1 drive burns at 2x CLV (constant linear velocity), Gen2
burns at 4x CLV, reads DVD-R/ROM at 6x, burns CD-R/RW (Gen1 8/4x, Gen2 16/8x)
- Cons:  Gen1 Rewrite slow (1x)

- RECORD: DVD-R(G)
Linux/DVDRTools fully supports!!!
- REWRITE:  DVD-RW
Alpha/Beta quality Linux kernel support available (separate download).


DVD+RW (Sony/Philips Independent Standard)

- Supporters:  Sony, Philips, some PC OEMs (e.g., HP)
- Design:  Independent, CAV (constant angular velocity) Consumer Format
(originally 3GB DVD-R+W back when Gen1 DVD-RAM was only 2.6GB -- circa 1998)
- Pros:  Very fast read (4-8x CAV), Fast CD-R/RW (12/10x)
- Cons:  No Gen1 Record support, Gen2 DVD+R Record not as player compatible as
DVD-R(G), 2.4x CAV DVD+R/RW is _slow_ on inner tracks (only 1.2-1.5x for first
1-2GB), non-DVD Consortium Standard

- RECORD:  DVD+R (Gen2-only -- e.g., HP DVD200i, but not 100i)
Linux/DVDRTools does _not_ support this.  Not sure ProDVD does either.

- REWRITE:
Alpha/Beta quality Linux kernel support available (separate download).


RECOMMENDATION

I'd either look at the latest 4x DVD-R(G) Pioneer DVR-104 (Retail: DVR-A04)
since it is the _only_ drive supported by DVDRTools for RECORD, and DVD-R(G) is
so widely read by so many players.  It's also cheap (~$0.75 for 1x DVD-R(G)
disks).  If you need to record DVD-R(G) in Linux, this is what you want!

Otherwise the new Sony Hybrid DVD-R/RW+R+RW drives look nice, although DVDRTools
might now support it.  They are fairly cheap too, under $300 at some places.  It
can't hurt supporting all formats (except DVD-RAM, which isn't important for 99%
of users).  This drive is already turning out to be popular, so support for it
in DVDRTools is inevitable (I assume).

Lastly, if you want a "long-term archiving" rewrite format, I'm partial to
DVD-RAM is the standard that finally killed all those proprietary methods long
ago (e.g., I've had a DVD-RAM drive since 1998). The "problem" with CD-RW,
DVD-RW and DVD+RW is that they use magneto-optical (MO) rewrite technology,
which is _unreliable_ during writes, and only have a ~3 year shelf-life (which
is why you should _always_ use CD-R over CD-RW for backups ;-) -- it adds
verification and a 2-sided cartridge option, and extends the number of rewrites
from ~1,000 to ~100,000, which nullifies most issues with MO and longevity.  The
"tradeoff" is that it is much slower, not very compatible outside of DVD-RAM
partners (because of all the extra laser/logic support), so it's not a
"consumer" format.  DVD-RAM is fully supported in Linux, has been since
inception (because its firmware is the same as its CD-PD predecessor.  The
latest Gen3 drives also do DVD-R(G) Recording, although DVDRTools doesn't
support it (ProDVD might?).  Oh yeah, the drives are _cheap_!  I just picked up
a Gen3 for $165!


-- 
Bryan J. Smith, E.I.            Contact Info:  http://thebs.org
A+/i-Net+/Linux+/Network+/Server+ CCNA CIWA CNA SCSA/SCWSE/SCNA
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