Switch to DVD backup media from CD?

On Sat, 04 Jun 2005 15:14:56 +0000, Arno Wagner wrote:


My main worry in migrating to DVD's is the potential loss of data over
a period of time,

That would be my concern also. You need a significanlty better than
"reads fine after burning" burn to accomodate ageing. c't does surface
analysis with professional equipment after test burns and many
combinations of writer/speed/medium are marginal or problematic. The
problem is not that there are no good combinations, but that it is
difficult to find them. In addition the manufacturers seem to change
their media over time and a firmware-upgrade to a writer can make things
better or worse so you cannot rely long-term on published test results.

Arno

I agree with that. So the question really is, does two DVD burns on
different media give a very good chance that at least one survives the
next five/ten years? This is of course on single-layer media, certainly in
the case of dual-layer, it would not be worth the risk.

Regards,

Pan

On Sat, 04 Jun 2005 05:22:52 +1000, Rod Speed wrote:


Which TV cards do you use?

DNTV Live!

How did you find them?

Not clear if you mean how did I discover them or how do I find
them to use. No real complaints except that the software is a
little less than perfect currently, not by much tho.

That was what I meant, thanks for the information.


I might think about implementing something like this myself.

I've had no regrets at all.

Sounds interesting for sure.

Yeah, rather radically changes the way I do things with TV recording.

You dont have to fart around finding big enough holes
in the tapes for what you want to record, just ensure
that the total space left on the hard drive is enough.

Yes, I've tired of doing that as well, and I've been thinking about an HD
recorder for a while as a means of solving that problem. Never thought of
using a PC to do it though


Yes, I got so tired of CRC errors, I brought a tape drive and
starting using that instead They are apparently quite reliable,

I gave up on those before I gave up on floppys.

Why?

Too unreliable.

Really? What problems did you have? I didn't lose a byte of data in the
admittedly short time I used them.


Although they are quite slow, I think it's
infinitely preferable to floppy's surely?

Sure, but I had a CD burner by then.

CD burners were very expensive in the time I switched to a tape drive. I
couldn't afford the burner, so the tape was the next best thing I could
get. At that time too, CD wasn't entirely proven for backup.


Perhaps that's true for the smaller ones,
but flash memory is now nearing CD sizes

Yes.

at competitive prices.

Cant agree with that at all.

Well, a quick survey of an online shop I use establishes a 512 pendrive at
£28 with an SD card at £18. This isn't as cheap as DVD media of course,

Thats what I meant by the prices not being competitive at all.

I can't really argue with that


I guess it comes down to what you want. I would prefer the convenience
of a 512 pendrive for carting data about at the prices quoted,

I use CD for that size. And had a CD burner
well before the pen drives ever showed up.

whereas you may prefer the raw savings
provided by the use of CD media.

Its not that so much as the fact that I move data around on the lan
or the net the bulk of the time and with the bigger volumes where a
CD makes sense, CDs are so cheap I dont care about the cost and
they are much more convenient to post, since you dont need to waste
any money on more than letter rate and dont need to get it back etc.

Yeah, I can see why it might be useful in your situation. For sure, CD has
it's uses even for me, but perhaps flash memory is more appropriate for my
usage patterns.


Each to his/her own I suppose

Indeed. They are quite useful if you want a portable mp3
player, but I dont bother with portable music at all, ever.

I do have an mp3 flash memory device, but I actually brought a pendrive
for data before that. So I have one each for both music and data.


Just wanted to personally thank you in advance for all
the help you've provided. Your advice has proven very
useful in helping me to choose to switch to DVD media.

No problem, thats what these tech groups are all about.

True, but I appreciate your advice all the same, particularly since you've
answered far more than the original question. Much obliged for your help.

My thanks also to everybody else who
replied in this thread. Much appreciated.

Regards,

Pan

Pan wrote in message
news
Rod Speed wrote

Yes, I got so tired of CRC errors, I brought a tape drive and
starting using that instead They are apparently quite reliable,

I gave up on those before I gave up on floppys.

Why?

Too unreliable.

Really? What problems did you have?

Forget the fine detail now, but one tape became
unusable, even tho it was mechanically fine.

I also had a hell of a problem with the tape hunting as
it was written, essentially because the data couldnt be
supplied fast enough and so it had to back up repeatedly.
This was with those damned floppy interface tape drives.

I didn't lose a byte of data in the admittedly short time I used them.

Although they are quite slow, I think it's
infinitely preferable to floppy's surely?

Sure, but I had a CD burner by then.

CD burners were very expensive in the time I switched to a tape drive.

Sure, I certainly used the tape drives before the CD burner,
but gave up on the tapes once the first CD burner was bought.

I couldn't afford the burner, so the tape was the next best thing
I could get. At that time too, CD wasn't entirely proven for backup.

It turned out to be considerably more reliable for me.

I guess it comes down to what you want. I would prefer the convenience
of a 512 pendrive for carting data about at the prices quoted,

I use CD for that size. And had a CD burner
well before the pen drives ever showed up.

whereas you may prefer the raw savings
provided by the use of CD media.

Its not that so much as the fact that I move data around on the lan
or the net the bulk of the time and with the bigger volumes where a
CD makes sense, CDs are so cheap I dont care about the cost and
they are much more convenient to post, since you dont need to waste
any money on more than letter rate and dont need to get it back etc.

Yeah, I can see why it might be useful in your situation.
For sure, CD has it's uses even for me, but perhaps flash
memory is more appropriate for my usage patterns.

Yeah, I agree that mine are a bit atypical there, I dont move much
stuff between physical machines that arent lan connected and I got
into the habit of plugging even foreign machines being worked on
into the lan effortlessly for easy movement of data between them.

Just wanted to personally thank you in advance for all
the help you've provided. Your advice has proven very
useful in helping me to choose to switch to DVD media.

No problem, thats what these tech groups are all about.

True, but I appreciate your advice all the same, particularly since you've
answered far more than the original question. Much obliged for your help.

No problem, happy to discuss almost anything except
say knitting which I know bugger all about |-)

Pan wrote in message
news
Arno Wagner wrote

My main worry in migrating to DVD's is the
potential loss of data over a period of time,

That would be my concern also. You need a significanlty better than
"reads fine after burning" burn to accomodate ageing. c't does surface
analysis with professional equipment after test burns and many
combinations of writer/speed/medium are marginal or problematic. The
problem is not that there are no good combinations, but that it is
difficult to find them. In addition the manufacturers seem to change
their media over time and a firmware-upgrade to a writer can make things
better or worse so you cannot rely long-term on published test results.

I agree with that. So the question really is, does two DVD burns on
different media give a very good chance that at least one survives the
next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the situation
where one has gone bad, before they have both gone bad and
you can just make another copy to replace the one gone bad.

While I did that with CDs when they were at the equivalent
maturity, it turned out that none went bad, so it was just insurance.

This is of course on single-layer media, certainly in
the case of dual-layer, it would not be worth the risk.

Yeah, and pointless given its price currently anyway.

On Sun, 05 Jun 2005 04:24:47 +1000, Rod Speed wrote:


I agree with that. So the question really is, does two DVD burns on
different media give a very good chance that at least one survives the
next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the situation
where one has gone bad, before they have both gone bad and
you can just make another copy to replace the one gone bad.

That makes sense, but sounds like a lot of management in the long run. How
do you schedule your checks on the media? Do you follow any patterns?

Regards,

Pan

On Sun, 05 Jun 2005 04:21:11 +1000, Rod Speed wrote:


Pan wrote in message
news
Rod Speed wrote

Yes, I got so tired of CRC errors, I brought a tape drive and
starting using that instead They are apparently quite reliable,

I gave up on those before I gave up on floppys.

Why?

Too unreliable.

Really? What problems did you have?

Forget the fine detail now, but one tape became
unusable, even tho it was mechanically fine.

That doesn't sound too good..... I might give a few of my tapes a whirl
and see what condition they are in.


I also had a hell of a problem with the tape hunting as
it was written, essentially because the data couldnt be
supplied fast enough and so it had to back up repeatedly.
This was with those damned floppy interface tape drives.

Yes, those are likely to be very slow. I had a parallel port drive myself,
but that was pretty slow as well. I think it was 4megs a minute.


I didn't lose a byte of data in the admittedly short time I used them.

Although they are quite slow, I think it's
infinitely preferable to floppy's surely?

Sure, but I had a CD burner by then.

CD burners were very expensive in the time I switched to a tape drive.

Sure, I certainly used the tape drives before the CD burner,
but gave up on the tapes once the first CD burner was bought.

Me too in that case. I brought the CD Writer with the expressed goal of
using it as a primary backup means, although I remember having quite a few
problems with it. At first I thought it was the drive because it was a
cheap one. But years after, I discovered that my motherboard had a known
IDE flaw with CD writers. As far as I remember, the problem was
inconsistent writing reliability.


I couldn't afford the burner, so the tape was the next best thing
I could get. At that time too, CD wasn't entirely proven for backup.

It turned out to be considerably more reliable for me.

Let's hope DVD does too


Just wanted to personally thank you in advance for all
the help you've provided. Your advice has proven very
useful in helping me to choose to switch to DVD media.

No problem, thats what these tech groups are all about.

True, but I appreciate your advice all the same, particularly since you've
answered far more than the original question. Much obliged for your help.

No problem, happy to discuss almost anything except
say knitting which I know bugger all about |-)

lol. I wouldn't ask me for advice on that subject either if I was you

Regards,

Pan

Pan wrote in message
news
Rod Speed wrote

I agree with that. So the question really is, does two
DVD burns on different media give a very good chance
that at least one survives the next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the situation
where one has gone bad, before they have both gone bad and
you can just make another copy to replace the one gone bad.

That makes sense, but sounds like a lot of management in the long run.
How do you schedule your checks on the media? Do you follow any patterns?

Not really. Dont need to check much since I use them for other
than backup anyway, so I will notice if some become unreadable.

Just do a check every year or so until I decided that they
werent going to die and checked less frequently than that.

Rod Speed wrote:
Pan wrote in message
news
Rod Speed wrote

I agree with that. So the question really is, does two
DVD burns on different media give a very good chance
that at least one survives the next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the
situation where one has gone bad, before they have both gone bad and
you can just make another copy to replace the one gone bad.

That makes sense, but sounds like a lot of management in the long
run. How do you schedule your checks on the media? Do you follow any
patterns?

Not really. Dont need to check much since I use them for other
than backup anyway, so I will notice if some become unreadable.

Just do a check every year or so until I decided that they
werent going to die and checked less frequently than that.

Its worth noting that the reflected layer is situated on the top surface
(label side)
of CDRs - any deep scratch here will destroy data - and this cannot be
repaired.
A scratch on the underside can be polished out, one on the label side can't.
"Printable" CDRs are better protected for this (thicker label layer)

The top surface is surprisingly thin (try using a penknife on a CD you don't
care about)

The reflective surface is in the middle of the disk with DVDs, so a surface
scratch
can't affect it..They are less tolerant of tiny everyday scratches and
fingerprints due
to the higher data density, though those can be polished out.

--
Mike

On Mon, 06 Jun 2005 00:26:20 +0100, Pan
wrote:

On Sun, 05 Jun 2005 04:24:47 +1000, Rod Speed wrote:

I agree with that. So the question really is, does two DVD burns on
different media give a very good chance that at least one survives the
next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the situation
where one has gone bad, before they have both gone bad and
you can just make another copy to replace the one gone bad.

That makes sense, but sounds like a lot of management in the long run. How
do you schedule your checks on the media? Do you follow any patterns?

I've got a good bit of data on CDR failure (based on hundreds of dead
and dying CDRs from the last decade), but my DVDs haven't started
failing yet. Other people's have. I'm running tests on them, but no
solid results yet. Generally, I wouldn't trust any burned media over
2 years. Lots of people (myself included) have burned discs much
older than that, but when they fail, that's when it starts, IME.

Here's what I've come up with.

To ensure longest data life on burned media (CDR or DVD):

- Test burn different brand media at full speed with verification and
find what works most reliably on your burner(s). My NECs like
RICOHJPN* media, with maybe 1 failure per 50 burns. I recently tried
CMC 8X blanks (blech - ordered the wrong media!), and got 1 out of 4
verification failures at 8x in 16 burns. All are fine at 4x,so I use
them at 4x for short-term data storage.

Remember that brand names are no indication of who actually made the
disc, and this week's Memorex may be completely different than the
ones you bought a month ago. The OEM media code is what counts, not
what's stamped on the label.

- Always burn important data below the rated max speed for the burner.
I burn at 1/2 max rated speed, except on 4x burners, where you have to
burn at 2.4x. I have lots of data showing that this dramatically
extends burned media life on CDR. This and verification make the
burns take a lot longer than they need to, but if data integrity is
important, this is the no-shortcut route.

- Always verify your burns. Even good quality media has bad discs
sometimes.

To help troubleshoot future problems:

- Always write the date, burner model, speed burned, media code, and
whether verified on the media.

- Some readers are better at pulling data from failing discs than
others. My LiteOn LTD163 DVD reader reads failing/dead CDRs that
Plextors, Teacs, and NECs are unable to read at all. No data on
failing DVDs, since I don't have any yet.

To keep your data safe long-term:

- Store it on a hard drive, and automatically back up that hard drive
to another hard drive, ideally in a different physical location to
protect from burglars and localized catastrophes. Be sure to verify
the backups now and again to make sure no glitches are at work in your
system.

- Once every so often, burn your data (primary or backups; there are
tradeoffs either way) to DVD. How often depends on how fast your data
changes and how important it is. Store these somewhere cool and dry
(I keep them in a big safe with other useful stuff).

For my family photos and such, I burn them to DVD once a quarter,
which means that my DVDs never (so far) have enough time to go bad
before another generation is in place. Losing all my data would
require the failure/loss of 2 hard drives and a stack of DVDs all at
once. A major fire could do this, but that's acceptable per my risk
management decisions. I could get around this by storing the backup
DVDs offsite.

Whatever you do, think through what can go wrong and what resources it
takes to cover it. A super backup plan is no good if you won't
actually pull it off, but every extra level of backup reduces the risk
of total data loss dramatically.


--
Neil Maxwell - I don't speak for my employer

Mike Redrobe wrote in message
. uk...
Rod Speed wrote
Pan wrote
Rod Speed wrote

I agree with that. So the question really is, does two
DVD burns on different media give a very good chance
that at least one survives the next five/ten years?

Its not that prediction that matters so much as carefully checking
the readability at a decent rate so that you can detect the
situation where one has gone bad, before they have both gone bad and you
can just make another copy to replace the one gone bad.

That makes sense, but sounds like a lot of management in the long run. How
do you schedule your checks on the media? Do you follow any patterns?

Not really. Dont need to check much since I use them for other
than backup anyway, so I will notice if some become unreadable.

Just do a check every year or so until I decided that they
werent going to die and checked less frequently than that.

Its worth noting that the reflected layer is situated on the top surface
(label side) of CDRs - any deep scratch here will destroy data - and this
cannot be repaired.

Sure, but its easy enough to avoid scratching that and you have
the media duplicated anyway even if the brown stuff hits the fan
and you manage to damage it that badly. You should notice that
sort of damage happening and can use the duplicate immediately
so you have at least 2 good copys at all times.

A scratch on the underside can be polished out, one on the label side can't.
"Printable" CDRs are better protected for this (thicker label layer)

The top surface is surprisingly thin (try using a penknife on a CD you don't
care about)

Sure, but the practical reality is that while kids particularly
can manage to obscenely damage the clear side of the
media, you dont see too many get badly enough damaged
on the label side to not be usable anymore.

The reflective surface is in the middle of the disk with DVDs, so a surface
scratch can't affect it..They are less tolerant of tiny everyday scratches and
fingerprints due to the higher data density, though those can be polished out.

Yes, but its also easy enough to avoid scratching
them at all with backup media that you care about.