Switch to DVD backup media from CD?

[Pan]

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

 

[Pan]

DNTV Live!


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.

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

Too unreliable.

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

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.

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

I can't really argue with that

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


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.

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.

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.

Regards,

Pan

 

[Rod Speed]

Rod Speed wrote

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.

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.

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.

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 |-)

 

[Rod Speed]

Arno Wagner 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.

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.

 

[Pan]

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

 

[Pan]

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.

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.

It turned out to be considerably more reliable for me.

Let's hope DVD does too

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

 

[Rod Speed]

Rod Speed wrote

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.

 

[Mike Redrobe]

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.

 

[Neil Maxwell]

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.

 

[Rod Speed]

Rod Speed wrote

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.

 

[J. Clarke]

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.

Have you addressed the dye chemistry in your tests? Different dyes have
different storage lives--some are only good for a few years, others are
much more stable. Not only do different manufacturers use different dyes,
but also some manufacturers make several lines of media with different dyes
(the more durable dyes are also more expensive I understand, but that might
just be marketing).

 

[Pan]

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.

I must admit that I don't test the compatibility of the media in the
drive, but I test all burn at full speed. With the batch I've been using
for the past year or so, I haven't seen a single bad burn.

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.

Yep, too true. Buying these discs is like a minefield. I had to establish
the background of the particular CD's I brought last time before
purchasing them.

- 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.

With modern burners, I always burn data at 4x. Higher speeds
apparently can increase vibration on the disk resulting in a less accurate
burn. I use 4x because that's my drive has a number of methods of burning
at higher speed. 4x is the maximum that can be extracted from the slowest,
most effective method.

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

That goes without saying

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.

Yes, that makes sense. Fortunately I've never had to extract data from bad
discs as of 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.

I do already as a matter of course for the fastest changing, most
important data.

- 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.

Yes, I've been thinking about the latter too, but I'm not sure where I
could store personal data offsite. I haven't quite figured out how I can
get around that problem yet. I suppose I could use an online drive service
and encrypt the files, but I still dislike trusting these firms to protect
the data

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.

I totally agree with you. That's the main reason I posted this thread
enquiring about the switch to DVD media. It's best to be safe than sorry

I appreciate the advice you've given. Thanks

Regards,

Pan

 

[Pan]

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.

Ah right, I thought you meant you do daily or weekly examinations of your
discs. That was starting to sound a bit scary to me in terms of management!!!

Regards,

Pan

 

[Pan]

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.

Ah, this is interesting. I wasn't aware of any of this. Thanks for the
information.

I must confess that my belief in DVD's was severely shattered when I
went to watch one of my DVD film discs and discovered that it wouldn't
play. After examining the disc, I was shocked to find a number of very
prominent small circles overlapping on the bottom-side of the disc, almost
like the disc had been physically scratched over and over in perfect
circles by UFO's!!! One other disc in the same collection had been
similarly affected. At first, I thought it was a physical defect in one of
the DVD drives, so I had to go through every other disc looking to see
what else was damaged. However, I found nothing at all. A bit later on, I
discovered that the damage was caused by DVD-rot and that the top surface
of the disc had also misted up. I managed to get the collection replaced,
but this was a real-wake-up when it came to DVD's.

Anybody else suffer anything like this? I have pictures to prove it if
anybody is interested.

Regards,

Pan

 

[Arno Wagner]

Neil Maxwell wrote:

Have you addressed the dye chemistry in your tests? Different dyes have
different storage lives--some are only good for a few years, others are
much more stable. Not only do different manufacturers use different dyes,
but also some manufacturers make several lines of media with different dyes
(the more durable dyes are also more expensive I understand, but that might
just be marketing).

I could imagine that longer life entails more precise manufacturing,
and/or more difficult to process dyes. At least that would make sense.

Still, the killer for CD/DVD as reliable storage medium is that
it impossible to determine media lifetime with reasonable effort.
If I need to spend many hours extra, I can afford something much
better than this low-end mass-market storage nightmare.

Arno

 

[Pan]

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.



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.


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

I have to agree with what Rod has said. Although it may be easy to
physically damage them, it is unlikely that anybody would place their
important backup archive into a situation in which the discs could be
damaged. Therefore, I don't really think that physical abuse is one of the
things you need to be too careful of, although of course it should be kept
in mind. Thanks for the information though, I learnt something

Regards,

Pan

 

[Rod Speed]

I must admit that I don't test the compatibility of the media in the
drive, but I test all burn at full speed. With the batch I've been using
for the past year or so, I haven't seen a single bad burn.


Yep, too true. Buying these discs is like a minefield. I had to establish
the background of the particular CD's I brought last time before
purchasing them.


With modern burners, I always burn data at 4x. Higher speeds
apparently can increase vibration on the disk resulting in a less accurate
burn. I use 4x because that's my drive has a number of methods of burning
at higher speed. 4x is the maximum that can be extracted from the slowest,
most effective method.


That goes without saying


Yes, that makes sense. Fortunately I've never had to extract data from bad
discs as of yet.


I do already as a matter of course for the fastest changing, most
important data.

Yes, I've been thinking about the latter too, but I'm not
sure where I could store personal data offsite. I haven't
quite figured out how I can get around that problem yet.

Many keep the personal backups at
work and the work backups at home.

Not hard to find someone local who is prepared to swap
backups either, providing offsite backups for both.

I suppose I could use an online drive service and encrypt the
files, but I still dislike trusting these firms to protect the data

I dont care about the risk with strong encryption.

 

[J. Clarke]

I could imagine that longer life entails more precise manufacturing,
and/or more difficult to process dyes. At least that would make sense.

No imagining required. Google "phthalocyanine".

Still, the killer for CD/DVD as reliable storage medium is that
it impossible to determine media lifetime with reasonable effort.

Just buy archival-rated media.

 

[Neil Maxwell]

Yes, I've been thinking about the latter too, but I'm not sure where I
could store personal data offsite. I haven't quite figured out how I can
get around that problem yet. I suppose I could use an online drive service
and encrypt the files, but I still dislike trusting these firms to protect
the data

I don't do this, but there are several options I've come up with.
Mine is all personal data, so time and budget is more of an issue than
corporate data. I also distrust online storage, and my data's big
enough to not be very practical for that.

- Good protection could be had by dropping off disc sets at a safe
deposit box. This takes time and energy, and the data's not available
nights and weekends, but it's secure, and you could leave the last 3-4
backups there. You could do this with removable HDs in cushioned
cases as well, and probably save yourself a ton of time feeding discs.
A set of 4-5 HDs would provide lots of redundancy and wouldn't cost
all that much.

- An easier bet would be to package them up and mail them to a friend.
This could be made very simple with fixed-price express mailers or
knowing the postage cost; just load up discs, seal the package, and
drop it at the post office or give to the mailman. If it's a good
friend, it would be available when you need it. I wouldn't do this
with HDs, due to the handling risks, but you could work up the
packaging if you wanted. You'd need to worry about encryption if your
data is sensitive.

There are lots of other ways to deal with it, but this second is what
I'd do if I were going to start, since my safe deposit boxes are about
20 minutes away, and I don't think I'd be reliable at dropping them
off.

 

[Neil Maxwell]

Have you addressed the dye chemistry in your tests? Different dyes have
different storage lives--some are only good for a few years, others are
much more stable. Not only do different manufacturers use different dyes,
but also some manufacturers make several lines of media with different dyes
(the more durable dyes are also more expensive I understand, but that might
just be marketing).

Not specifically, except for tracking which is which, as I have
nothing more sophisticated than a microscope for failed disc analysis
(which is not very helpful). So far, the Taiyo Yuden Japanese CDRs,
which are identified as cyanine (type 1) dye, are the only ones that
haven't completely failed on me. I started using these around 1998,
and most are still reading well, though some are starting to read
slowly at the outer edges of the disc, which is a sign of impending
failure.

The discs considered archival back in the old days (Mitsui, Ricoh/KAO,
Kodak Gold/Silver - Phthalocyanine (Type 5)) have all died or are very
near dead. I mostly used these prior to 1998, when I switched over to
the TYs almost exclusively due to failures. I also started recording
at half max burner speed, so the post-98 data has different initial
conditions than earlier data. Likewise, discs identified as cyanine
(type 0) all failed early on, and include such bottom-feeder
manufacturers as CMC, so I assume there's a big difference between
cyanine types 0 and 1.

It's made much more complicated by the fact that dye layers and
reflective coatings are constantly being changed by the manufacturers,
and even if my 2000 TY discs are still fine, it doesn't mean that TY
discs I burn today will be good in 5 years. Accelerated testing
results are useless here, IMO.

I just assume all CDRs and DVDs I burn will fail somewhere between 2
and 5 years out, and it saves me quite a lot of worry.