Preserving Old Valuable Tapes

[ppppenguin]

M-Disk is expensive, bulky and unproven.

http://www.extremetech.com/computing...sts-1000-years

There is no such thing as a perfect archival storage solution. In my opinion, for ordinary amounts of data (say up to a few Terabytes) multiple HDDs are the best current solution. They are cheap, compact and easy to copy. The MTBF is a lot longer if they are switched off.

[GMB]

... just make sure that every time you make a copy you verify that it IS a copy.

Everyone merrily assumes that digital replication means no errors. This is isn't true! Modern PC's filestores have a miserable level of validation.

Far too much emphasis gets places on the idea that data becoming corrupt through media failure etc. But discs especially have other little tricks which don't always get detected quickly enough. The classic is to write valid data to the wrong place. Another is to fail to write at all, leaving valid but now out of date data in place.

You have to verify by independently storing sumchecks (like MD5 etc.) that the files that your PC says it has copied actually contained the data you thought they did. And thanks you modern clever but crappy systems, you have to go so great lengths to be sure that when you read back a copy for validation that you actually are reading it at all (watch out for caching).

It's hard!

[ricard]

Sometimes I wonder if the ideal medium for long term preservation of audio would be - wire. Apart from corrosion or extreme heat causing it to melt, the wire used for wire recorders is extremely durable. There are wire recordings over 100 years old which are still playable and where the media doesn't degrade because of aging. So as far as documented long-term stability, wire would seem to be the choice.

Not too serious perhaps, and there are problems with limited frequency response, inability record stereo, etc. But if I had to make a 'time capsule' with an audio recording in it, I might choose wire.

I've read in several place that those dealing with archiving media on a large scale a while ago switched from trying to maintain machines on which the media could be played back, to digitizing the material, and continually making new digital copies. This mainly because it became impractical to continue and maintain all sorts of playback equipment - just think of all the video formats there, not to mention keeping all machines in working order with aging components.

My personal opinion is similar to what's been made above: make a digital copy, re-copy it to new media regularly (especially when new interface technology comes up making old interfaces outdated, like the move from IDE to SATA), and keep the original analog media at the same time. I'd choose hard drives as they seem to be the most durable digital media available. Especially if not used very often (but still from time to time so they get some excersise) and stored in a reasonable environment.

[brenellic2000]

Interesting propositon, Ricard, but wire doesn't have the dynamic range that tape or vinyl has... and there are no wire recorders of post 1950s technology.

Which brings us full circle to the best proven long term storage medium for tape is... tape! - provided it is of stable stock, preferably pre mid-1970s, to avoid binder degradation. I rest my earlier case, M'Lud.

Barry

[Phil G4SPZ]

I couldn't agree more. Kept in dry storage at reasonable temperatures, tape has got to be one of the most stable media. I have a number of tapes from the early 1960s and cassettes from the 1970s (which have not been stored particularly well ) that are still in perfect playable condition.

I submit that the only type of media that really needs careful preservation is anything digital. I have 'lost' more digital music and data files than anything on records, tape or paper, due to computer failures or the vagaries of iTunes.

Think about it; tape, like shellac and vinyl, is essentially an analogue mechanical storage system, and given adequate mechanical protection, such systems require no power and should last indefinitely. The same cannot be said for digital storage systems of any type, including floppy disks and CD-ROMs.

[ms660]

Transfer the tape to vinyl, store the original tape as suggested, put the vinyl in a safe container.

Lawrence.

[brenellic2000]

Now here is an original thought which combines fool proof digital technology and proven archival qualities - a Pianola running on punched parchment rolls! OK it may lack the sweetness and warmth of analogue tape and vinyl but it beats MP3s anyday - and it's still 'digital'!

... perhaps not such a very good thought...

Barry

[Ian212121]

Originally Posted by ppppenguin

M-Disk is expensive, bulky and unproven..

Hmm- never heard DVDs described as bulky before. As for expensive- each to his own but £3 a disc and £50 for a burner sounds good to me.

Originally Posted by ppppenguin

....The MTBF is a lot longer if they are switched off.

I've been around IT too long to believe that when you switch something off that there's a 100% chance of being able to switch it on again.

[ppppenguin]

Originally Posted by Ian212121

Hmm- never heard DVDs described as bulky before. As for expensive- each to his own but £3 a disc and £50 for a burner sounds good to me.

For 1TB of data, approximately:
Mdisc/DVD: £600, 3000cubic cm (excluding cases); HDD: £50, 30cubic cm

Even if we allow for duplicate HDD and risk a single uncased Mdisc/DVD copy HDD is still much cheaper and smaller.

Originally Posted by Ian212121

I've been around IT too long to believe that when you switch something off that there's a 100% chance of being able to switch it on again.

I believe it to be true that there's a 100% chance that anything will fail given enough time.

[ricard]

Originally Posted by Phil G4SPZ

I couldn't agree more. Kept in dry storage at reasonable temperatures, tape has got to be one of the most stable media. I have a number of tapes from the early 1960s and cassettes from the 1970s (which have not been stored particularly well ) that are still in perfect playable condition.

I submit that the only type of media that really needs careful preservation is anything digital. I have 'lost' more digital music and data files than anything on records, tape or paper, due to computer failures or the vagaries of iTunes.

Think about it; tape, like shellac and vinyl, is essentially an analogue mechanical storage system, and given adequate mechanical protection, such systems require no power and should last indefinitely. The same cannot be said for digital storage systems of any type, including floppy disks and CD-ROMs.

My problem with tape for long-time storage, is while I also have tapes from the 1950's and 1960's which play fine, I also have tapes that don't play fine, and even if they play fine now, there's no telling how the binder chemistry will hold up for another, say 50 years. Sure, the past 50 years have shown a good track record for some tapes but I don't know how much I'd bet on another 50 years. The problem is we don't know which tape formulations today will hold their own over time in the future.

I still agree that digital is rather volatile, and requires continual re-duplication, with associated risks of data loss at each copy instance.

[GMB]

Kept in dry storage at reasonable temperatures, tape has got to be one of the most stable media. I have a number of tapes from the early 1960s and cassettes from the 1970s (which have not been stored particularly well ) that are still in perfect playable condition.

Not my experience going back to my days with mainframe computers, storing large quantities of tapes in air-conditioned luxury. The constant problems were print-through and the coating becoming sticky. We had to endlessly cycle tapes through cleaning machines to prevent print-through building up and to keep the coating from failing.

One thing that makes a huge difference between the various solutions is the failure mode. Anything analogue has the built-in advantage of degrading gradually, which means you never get the original back perfectly, but you usually get something.

Digital systems all turn on the actual digital encoding used. The megga-snag with HDD storage is that a common failure mode is total failure - quite hard to get a tape to do that (unless the building burns down).

The thing that annoys me greatly is that hardly any PC-based digital technology gives any indication of how hard it is struggling. Thanks to error correction techniques you just don't know how close to the edge you are.

[ppppenguin]

Originally Posted by GMB

Digital systems all turn on the actual digital encoding used. The megga-snag with HDD storage is that a common failure mode is total failure - quite hard to get a tape to do that (unless the building burns down).

That is why it's worth keeping more than 1 copy, in more than 1 place. If you're a pessimist then use different makes of HDD. At least they are cheap and small enough to do this.

Originally Posted by GMB

The thing that annoys me greatly is that hardly any PC-based digital technology gives any indication of how hard it is struggling. Thanks to error correction techniques you just don't know how close to the edge you are.

HDDs actually do have a mechanism to do this: http://en.wikipedia.org/wiki/S.M.A.R.T. It's far from a full solution. As other people have mentioned, it is entirely possible and sesnible to put data integrity checks on digital media.

[jamesperrett]

CD's/DVD's can be tested for correctable errors that will show up problems well before they become unreadable. I check almost every CD/DVD that I burn.

James.

[GMB]

I check almost every CD/DVD that I burn.

How?

I have not encountered S.M.A.R.T or indeed any software that seemed to help much with error reporting (should be a core OS feature in my books).

I would just add that my ancient experience on mainframes was that hardware devices are pretty hopeless at spotting problems. We added massive end-to-end validation for our filestore system and this detected very many more problems than the hardware ever admitted to, this being because the hardware itself has a rather narrow view of what it is doing.

A concern with the PC generation of storage devices is that many of them have difficulty distinguishing between real hardware errors and artefacts of the way they work (e.g. finding an error check code wrong is their way of knowing that the heads are in the wrong place or the rotation rate is wrong).

[julie_m]

Digital can degrade gracefully, if you let it.

If the storage format is uncompressed, one bit reading wrongly won't make a great amount of difference -- the chances are that low-pass filtering in the analogue domain will take care of it.

If the storage format is compressed, it can make recovery harder, because losing even one bit now affects a larger amount of data.

If the storage format is proprietary, and has not yet been successfully reverse-engineered, all bets are off.

[brenellic2000]

AJS raises an interesting point. If one regularly defragments the hard disc and the recorded data was in compressed form, but scattered, prior to a defrag, is there a danger of data becoming corrupted over time?

Barry

[jamesperrett]

Originally Posted by GMB

How?

Plextools with a suitable Plextor drive.

If you don't have a suitable Plextor drive you could also search for Opti Drive Control or Nero's Drive Speed which work with certain other drives.

James.