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From: RonTheGuy on 24 Jun 2010 22:49
In article <i00dmv$nj8$2(a)news.albasani.net>, Shaun <sheep(a)sheep2.net>
wrote:

> On 6/24/10 1:58 PM, RonTheGuy wrote:
> > In article<isw-EA2C11.10193524062010@[216.168.3.50]>,
> > isw<isw(a)witzend.com> wrote:
> >
> >> In article<1jkkz7f.1kqn24yxzdyqlN%RonTheGuy(a)null.invalid>,
> >> RonTheGuy(a)null.invalid (Ron) wrote:
> >>
> >>> I have a backup set on DVD-R media made by Retrospect 6 on my G5. Tried
> >>> to do an incremental backup recently after not backing up for a while;
> >>> Retrospect now thinks all my backup disks are blank. I checked the
> >>> internal optical drive; it can still burn CD-R and still read DVD media
> >>> burned on other machines. Where do I go from here?
> >>
> >> What does Finder think about those DVDs? Does it show that there are
> >> files on them?
> >>
> >> Isaac
> >
> > Finder on the G5 thinks the disk is blank. So does the finder on my MBP.
> > I'm mystified; this isn't what I expect to see on Retrospect backup
> > media. All the disks from this backup set that I've tried show up as
> > blank.
>
> Bit of a long shot-- but maybe you accidentally storesd some blank disks
> in your safe place rather than the ones you burned the backup on? Check
> your DVD spindle to see if you've got some recorded ones sitting there.

That's not it. I marked all the disks in the set. I must have done
something stupid but haven't figured out what yet. What David Empson
said makes sense about the finder not being able to see the data. Just
don't know why Retrospect seems unable to read the disks.
From: nospam on 24 Jun 2010 23:00
In article
<not-9A8C92.19494924062010(a)24-158-227-212.dhcp.leds.al.charter.com>,
RonTheGuy <not(a)null.invalid> wrote:

> That's not it. I marked all the disks in the set. I must have done
> something stupid but haven't figured out what yet. What David Empson
> said makes sense about the finder not being able to see the data. Just
> don't know why Retrospect seems unable to read the disks.

try a different dvd drive.
From: isw on 24 Jun 2010 23:23
In article <1jkn26v.vy7l3rvp90t5N%dempson(a)actrix.gen.nz>,
dempson(a)actrix.gen.nz (David Empson) wrote:

> isw <isw(a)witzend.com> wrote:
>
> > In article <1jkkz7f.1kqn24yxzdyqlN%RonTheGuy(a)null.invalid>,
> > RonTheGuy(a)null.invalid (Ron) wrote:
> >
> > > I have a backup set on DVD-R media made by Retrospect 6 on my G5. Tried
> > > to do an incremental backup recently after not backing up for a while;
> > > Retrospect now thinks all my backup disks are blank. I checked the
> > > internal optical drive; it can still burn CD-R and still read DVD media
> > > burned on other machines. Where do I go from here?
> >
> > What does Finder think about those DVDs? Does it show that there are
> > files on them?
>
> If they are from a Retrospect backup set, then Finder won't see
> anything. Retrospect uses a proprietary disc format on optical media,
> based on packet writing. The disc has no standard file system,
> directory, etc. and nothing other than Retrospect understands it.

I wasn't suggesting that Finder could *read* the discs; just that it
would show that *something* was on them -- or not.

I know that Retro used to use proprietary formats on tapes, but AFAIR it
was always possible to see that *something* was on those tapes even if
you couldn't actually read them. And I have always thought that optical
disc formats were constrained by the drive specifications to a large
extent -- you cannot persuade a drive to write over an already finalized
disc (to destroy the data), for instance.

Isaac
From: isw on 24 Jun 2010 23:29
In article
<not-8FF026.10581524062010(a)24-158-227-212.dhcp.leds.al.charter.com>,
RonTheGuy <not(a)null.invalid> wrote:

> In article <isw-EA2C11.10193524062010@[216.168.3.50]>,
> isw <isw(a)witzend.com> wrote:
>
> > In article <1jkkz7f.1kqn24yxzdyqlN%RonTheGuy(a)null.invalid>,
> > RonTheGuy(a)null.invalid (Ron) wrote:
> >
> > > I have a backup set on DVD-R media made by Retrospect 6 on my G5. Tried
> > > to do an incremental backup recently after not backing up for a while;
> > > Retrospect now thinks all my backup disks are blank. I checked the
> > > internal optical drive; it can still burn CD-R and still read DVD media
> > > burned on other machines. Where do I go from here?
> >
> > What does Finder think about those DVDs? Does it show that there are
> > files on them?
> >
> > Isaac
>
> Finder on the G5 thinks the disk is blank. So does the finder on my MBP.
> I'm mystified; this isn't what I expect to see on Retrospect backup
> media. All the disks from this backup set that I've tried show up as
> blank.

Usually, there is some visible change in the appearance of an optical
disc that has been written; can you see something like that?

What happens if you try to write on one of the Retro discs? If you can
do that, and the "new" data is all correct, then there is no way the
disc could have been written by Retro previously.

Isaac
From: David Empson on 25 Jun 2010 01:43
isw <isw(a)witzend.com> wrote:

> In article <1jkn26v.vy7l3rvp90t5N%dempson(a)actrix.gen.nz>,
> dempson(a)actrix.gen.nz (David Empson) wrote:
>
> > isw <isw(a)witzend.com> wrote:
> >
> > > In article <1jkkz7f.1kqn24yxzdyqlN%RonTheGuy(a)null.invalid>,
> > > RonTheGuy(a)null.invalid (Ron) wrote:
> > >
> > > > I have a backup set on DVD-R media made by Retrospect 6 on my G5. Tried
> > > > to do an incremental backup recently after not backing up for a while;
> > > > Retrospect now thinks all my backup disks are blank. I checked the
> > > > internal optical drive; it can still burn CD-R and still read DVD media
> > > > burned on other machines. Where do I go from here?
> > >
> > > What does Finder think about those DVDs? Does it show that there are
> > > files on them?
> >
> > If they are from a Retrospect backup set, then Finder won't see
> > anything. Retrospect uses a proprietary disc format on optical media,
> > based on packet writing. The disc has no standard file system,
> > directory, etc. and nothing other than Retrospect understands it.
>
> I wasn't suggesting that Finder could *read* the discs; just that it
> would show that *something* was on them -- or not.
>
> I know that Retro used to use proprietary formats on tapes, but AFAIR it
> was always possible to see that *something* was on those tapes even if
> you couldn't actually read them. And I have always thought that optical
> disc formats were constrained by the drive specifications to a large
> extent -- you cannot persuade a drive to write over an already finalized
> disc (to destroy the data), for instance.

Having a look at some of my Retrospect 6 backup CD-Rs: attempting to
mount it with Finder in Snow Leopard does nothing (no icon, no message
about an unreadable or blank CD). System Profiler or Disk Utility shows
the Retrospect volume name (sequence number and backup set name), and
that it has a file system called "retrospectcd".

No obvious difference between a full CD and a partly full one.

Looking at the written surface of the CD-R, there is a wider than usual
unwritten area near the centre ring about 3 mm across (possibly with a
very thin table of contents - just a slight hint), and data is written
outwards until the disc is nearly full (seems to be a somewhat variable
outer edge margin, perhaps based on how close it was when the previous
backup completed).

I've hardly ever used DVDs with Retrospect but I expect the same general
mechanism applies.


The OP's problem is likely to be one of these:

(a) The DVDs have degraded so the drive is unable to read the data any
more.

(b) That particular DVD drive doesn't like "unusual" disc formats.

(c) That particular DVD drive doesn't like that particular brand or type
of media.

All three might be resolved by trying a different drive.

--
David Empson
dempson(a)actrix.gen.nz
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