Acting upon a sudden uncontrolled impulse, because I had some time and some money to waste this afternoon and since I was walking through the 12th arrondissement of Paris (where all the Chinese computer hardware retailers are located), I bought myself a DVD±R[W] drive (burner, I mean). A Plextor PX-708A, to be precise (whose maximal burning speeds are: 8× for DVD+R, 4× for DVD+RW, 4× for DVD−R, 2× for DVD−RW, 40× for CD-R and 12× for CD-RW; reading speeds are 12× for DVD-ROM and 40× for CD-ROM); I've always bought Plextor burners previously and I've been quite satisfied, so I think I can recommend them.
The difference between ‘+’ and ‘−’
was completely unintelligible to me, and still isn't perfectly clear,
but here is a
(partial) explanation. (Unfortunately, Google isn't of much help here,
since it doesn't distinguish "dvd+r" from
"dvd-r", say.) Basically, ‘+’ is less
compatible with existing DVD-ROM
drives, but in counterpart can be written incrementally and without
risk of buffer underrun or such annoyances, whereas
‘−’ is much closer to CD-R[W].
Incidentally, ‘−’ is supported by the people who came up with the
DVD (same DVD logo), whereas ‘+’
is sponsored by a different group
(and the logo on disks is different). Apart from that, the disks have
the same size and—except for an explicit marking—are not
recognizable (both have the same purplish hue, for example, for Verbatim disks with
AZO-based dyes; strangely enough, their
DVD−R are made in Taiwan whereas their
DVD+R are made in India). Their capacity is the same
(around 4.4 gigabytes—meaning around 4.7 billion bytes—for
single-sided single-layer disks) and the price also seems to be
precisely the same.
To burn DVDs under Linux, I've tried DVD+RW-tools,
and they seem to work (although I've had some strange symptoms here or
there); despite the name, they will also work with
DVD−R[W], not just ‘+’. And the name
(growisofs) is also ridiculously unintuitive, but the
program in question is also able to, say, record a cramfs
image on the medium, not just grow an ISO9660
filesystem. Plain old cdrecord
won't work; and although there is a special different version
(cdrecord-prodvd) which will, I don't
recommend using it, were it only for the fact that it has a highly
obnoxious (and non-free) license—you need a “key” of
some sort to do the writing, and you don't get access to the source
code, and you might not even be able to use it commercially. There is
also a free fork of cdrtools (the kit which includes
cdrecord) called dvdrtools
which might be useful, but I haven't tried it yet.
Anyhow, it seems to work. Well, the DVDs I've recorded (whether ‘+’ or ‘−’) weren't readable by my DVD-ROM drive, but it's very old and mostly broken anyway, so I'm not really surprised. The burner itself is able to read the disks it wrote (I checked them thoroughly), which is what I mostly care about because I intend to use DVDs for backups.