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Gavin is correct, I erred. The capacity is 4.7GB for single-layer, 8.5GB
for double-layer, 9.4GB for double-sided and finally 17GB for double-sided,
double-layer.

DVD-RAM supported by Hitachi is 2.6GB per side, for a total of 5.2GB.  It
records at 1.352Mb/second (faster than a CD-R, but still much slower than
DDS3 or DLT.)  The media is $80 per unit.  It might be $40 by year's end.
It will take a few years for it to drop to $1 like CD-R.  The capacity
should be increased to match DVD-ROM at 4.7GB per side, next year.

DVD+RW supported by Sony and others is 3.0GB per side.  The Sony web site
does not have the transfer rate information but I expect it is comparable
to DVD-RAM.


Kind regards,

Denys. . .

Denys Beauchemin
HICOMP America, Inc.
(800) 323-8863  (281) 288-7438         Fax: (281) 355-6879
denys at hicomp.com                             www.hicomp.com


-----Original Message-----
From:   Gavin Scott [SMTP:[log in to unmask]]
Sent:   Monday, 24 August, 1998 11:21 AM
To:     [log in to unmask]
Subject:        Re: Re[2]: DDS-3 vs. DLT? Reliability?

Denys writes:
> DVD is supposed to hold up to 9.4 GB.  This is double-sided, double-layer
> DVD.

IIRC, that's the *single* sided double layer capacity.  Double sided would
be twice that.  I don't know if the second side can be read at the same
time as the first side potentially (i.e. does the spiral track go the
other way (if the track is even spiral anymore)).

>From what little I've paid attention to, it sounds as though there will
be multiple -R (writeable) formats using the DVD disc technology, and
all of them seem to have less capacity than a native (pressed?) DVD, so
it sounds as though it may never(?) be possible to copy a DVD-ROM format
disc.

> Finally media cost is going to be higher for DVD than for DDS or DLT.

If you're trying to store 100GB, then yes, but if you just want to store
3GB, DVD-R is almost certainly going to be dirt cheap eventually as CD-R
is today.

G.