Skip navigation
This discussion is archived

Archiving DV data - Longevity of magnetic media & other alternatives

2721 Views 12 Replies Latest reply: Dec 17, 2009 2:37 AM by Alchroma RSS
Anthony M Kassir MD Level 2 Level 2 (215 points)
Currently Being Moderated
Sep 27, 2009 6:49 AM
I'm sure this topic has come up several times over the years but I thought it's worth an update now that Blu-Ray is becoming more affordable and widespread.

A few years ago, I was advised to use magnetic tape to archive my video. This means keeping my original magnetic tapes and making another backup copy, using tape. This strategy has the advantage of being rather cheap and magnetic tape is supposed to be a pretty good way to archive video. However, I just had an experience that makes me question the wisdom of this strategy.

I had some 6- to 8-year-old Sony digital 8 (not MiniDV) tapes that I tried to recapture recently, but found the tapes have gone bad. The time code is shot and so is the audio, on every one of 22 tapes. They were stored in a dark drawer in my house, a few feet underneath my TV. (I wonder if the proximity to my TV led to premature dropouts?) The video is priceless, the first few years of my children's lives. Fortunately I have a backup copy of the data on hard disk (not tape), even though it was captured using an old version of iMovie several years ago. (I tested the Digital 8 camera by recording and playing back a few minutes of video on a new tape, and it was fine, so it wasn't the camera.)

If electromagnetic interference from my TV isn't responsible, that suggests the typical shelf life of magnetic tape is something like 5 or 6 years, and that's not very good.

I've read that hard disks aren't suitable for archiving data, because of the possibility of hardware failures (which eventually will happen) and the inherent impermanence of data stored on any kind of magnetic media. I'm not sure what the time frame is for data loss on a hard disk, but I'm guessing maybe 10 years if there is no hardware failure.

In any case, losing the data on those tapes was a wake-up call. I got to work and over the past 3 weeks captured (to hard disk) video from all the MiniDV tapes I've recorded in the last 3 years. I hadn't previously backed up these tapes. Thank goodness these tapes were still okay. They were stored in a different location, but I'm not sure if this made the difference.

Now I've finished capturing all my tapes and will be burning the unedited data to Blu-Ray gold archival discs, for safekeeping. Delkin makes these discs and they're expensive, and I had to add the cost of a Blu-Ray burner, but hopefully they'll last a good while. Delkin claims the data will be safe for 200 years.

I can't think of any safer way to archive video data than archival quality gold Blu-Ray media, except maybe Magneto-Optical discs which I don't ever hear of anyone using anymore.

I'll be interested to read the experiences of other people regarding the longevity of magnetic tape and other means of archiving video.
PowerMac G5 Quad 2.5 GHz; Intel iMac 3.06 GHz; MacBook Pro 3.06 GHz, Mac OS X (10.5.8)
  • Ian R. Brown Level 6 Level 6 (17,405 points)
    I'm sure there is no definitive answer as nobody will know (for certain) the merits of any of these things for at least 50 years!

    Extremely cheap, though probably less permanent solutions, are to back up a tape onto 3 standard DVDs.

    An even cheaper solution is to simply burn the tape onto a DVD in iDVD etc.

    Yes, this second suggestion will reduce the quality from DV, but it will still be pretty good and capable of being recaptured and edited in FCE, or whatever is around then.

    Whilst you wouldn't make a video from a DVD by choice, if you wanted ultimate quality, family archives are unlikely to receive the same critical viewing.
    24" 2.8 GHz (Penryn) 4GB RAM iMac + LaCie d2 Quadra 500GB HD, Mac OS X (10.5.2), FCE 4.0.1 + FCS 2 etc.
  • Michel Boissonneault Level 5 Level 5 (4,765 points)
    Anthony M Kassir MD wrote:
    Now I've finished capturing all my tapes and will be burning the unedited data to Blu-Ray gold archival discs, for safekeeping. Delkin makes these discs and they're expensive, and I had to add the cost of a Blu-Ray burner, but hopefully they'll last a good while. Delkin claims the data will be safe for 200 years.


    Hi(Bonjour)!

    I hope that BR DVDs will reach a wide installed base in computer world, a thing that is not acquired right now.

    The problem with all archive supports is the availablility of hardware able to read material. (do you have any beta tape in your atic? try to find a beta VCR today, same thing as 8 tracks cassette )

    Large broadcaster corporation use servers to store new and older material. Servers solution seems to be more reliable than tape or DVD-ROM solution as servers are here to stay, they evolve with their logical structure and operating system. They are redundant system as there is multiple backup and unit in their structure.
    But even with servers, we need software player that support codecs used in archivind process.

    Servers are not a solution for consumer, they are expensive to buy and support.

    Hard drives are a solution for mid-term storage. Your computer in the future will have to support the hierarchical files structure, a thing that not change rapidly (do you remeber the Macintosh File System, back in Mac OS system 8?) and codec used.

    Tape storage in best conditions and the fact that they are played once a year may help to keep them safe. I read my beta tapes from 1985 today, I read VHS from 1990, I read old Hi8 from 1990, I read miniDV from 2002 today.

    CD are better in long term staorage than DVD. I don't know for BR DVD but their popularity is a concern for me.

    Michel Boissonneault
    PowerMac G5 dual 2.3, 4.5 Go, Apple Cinema display HD 23", FX-1, FCS 2, Mac OS X (10.5.8), Ati Radeon X1900GT G5 edition, and iMac G4, FCE 4.0.1, macuser since 1988
  • Ian R. Brown Level 6 Level 6 (17,405 points)
    There have always been the "scare" stories of things not lasting and I must have heard many of them.

    Frequently they turn out to be just that ...... stories......... like the dramatic headlines in newspapers that barely contain an iota of the truth.

    I'm not saying they won't deteriorate, everything does, but probably nowhere near as quickly as the prophets of doom would have us believe.

    Unfortunately, that doesn't solve our problem.

    I suppose the only reasonably secure method is to keep at least 2 backups on different formats and be prepared to continually update them as technology advances.
    24" 2.8 GHz (Penryn) 4GB RAM iMac + LaCie d2 Quadra 500GB HD, Mac OS X (10.5.2), FCE 4.0.1 + FCS 2 etc.
  • Alchroma Level 6 Level 6 (16,875 points)
    They were stored in a dark drawer in my house, a few feet underneath my TV.


    This may be the reason for the rather short life of the tapes. If they are exposed to power cables (EM fields), amplifiers (power supplies) or magnetic fields (unshielded speakers) there's a good chance the info on them will get scrambled.

    This may or may not be the cause as it can the actual quality of the tape itself.
    My personal thoughts are to keep tapes and make another backup of some type using Archival Media. Sorta like "two heads are better than one" for that irreplaceable stuff.

    See here:
    http://discussions.apple.com/click.jspa?searchID=-1&messageID=10043854

    Al
    Mac Pro 2.66 Quad, Mac OS X (10.5.6)
  • MartinR Level 6 Level 6 (14,560 points)
    Hello Anthony,

    The challenges with long term storage & backup are +media degradation+ and +technological obsolescence+. Whatever you do, you should plan to back up onto at least 2 different types of media, store them properly, and plan to +refresh your backups+ periodically and/or as changes in technology may require.

    For video, I would 1) keep all original tapes; 2) dupe each tape to another top quality tape; 3) backup to 2 different top-quality hard drives in separate enclosures 3) store in different locations at least one of which is not on premises. Oh, and keep the appropriate technology around so you can actually use the media years hence. Nothing is permanent, however, and each type of media has its own limitations.

    Regardless of media, don't go cheap - get the best quality media you can find. However, I would still not rely on optical media for long term retention. If you must use optical media, look for media that use +AZO dyes+ and +silver or preferably gold reflective layer+, not organic dyes (phthalocyanine or cyanine) and not aluminum reflective layer that are typically used.

    Magnetic tape can have a very long life if stored properly. For example, I have VHS tapes recorded over 25 years ago that still play perfectly. I dupe them about every 8-10 years and have also duped them to miniDV and captured the video to hard drives. There is only 1 that ever went bad, and it was a cheap tape a friend had given me - says something about buying quality in the first place. miniDV tapes are even better quality than the best VHS tapes were. Your tapes were probably damaged by EMI from your TV and the cables around it.

    The key is proper storage - clean, dry, vertical, rewound and away from significant variations in temperature & humidity and definitely away from sources of EMI.
    MacBookPro 2.66GHz/4GB/5.5TB, Mac OS X (10.5.7), iMacG5/2.0GHz/2GB, eMac/1.25GHz/1GB. Too much other gear.
  • Matti Haveri Level 6 Level 6 (8,840 points)
    1) keep all original tapes; 2) dupe each tape to another top quality tape; 3) backup to 2 different top-quality hard drives in separate enclosures


    I've been doing this with iMovie 1-6. I have stored the edited data on harddisks as max 9 minute 27 sec .dv streams. Those are very fast to import to iMovie or via this shortcut via the Finder:

    http://www.sjoki.uta.fi/~shmhav/iMovieHD_6_bugs.html#quick_DVimport

    I've been glancing FCE and might finally switch to it from iMovie.

    ...but switching to FCE would mean that I should convert my .dv archives to DV-encoded .mov, right?

    Converting massive amounts of .dv to .mov isn't tempting but I guess there is no other way to easily get fast access to my video archives if I switch to FCE?

    BTW, it seems that converting .dv to DV-encoded .mov and back to .dv (via QT Player Pro) loses the embedded timecode (iMovie displays "unknown" as the capture date). So is the .dv -> .mov conversion lossy in this respect??
    PowerBook G4 1.25GHz 15 FW800, QT 7.6, iMovie HD 6.0.3, iDVD 6.0.4, Mac OS X (10.5.6), I don't benefit from any link
  • Tom Wolsky Level 10 Level 10 (104,605 points)
    You can use the .dv files in FCE. It just means you have to render the audio. A bit of a pain, but probably less painful then recompressing it all.
    15" 2.4G MacBook Pro, Mac OS X (10.6.2)
  • David Chatterton. Calculating status...
    Magnetic tapes suffer from the phenomenon known as print-through whereby the magnetic particles storing the data tend to magnetise the adjacent layers in a reel. (With old analogue audio tapes, an echo or pre-echo is quite noticeable.) To reduce these effects, it is recommended that the tapes be rewound every few years.

    BTW, storing magnetic tapes or discs near a CRT TV set is not a good idea because colour TVs generate a powerful magnetic field to de-gauss the shadow mask each time they are switched on.

    The trouble with digital encoding is that the effects of print-through are not noticeable until it is too late. In practice, magnetic tapes are not much good for periods in excess of 10 years. Apart from the tedium of rewinding, this exercise runs the risk of causing terminal damage to the tapes. I know of several magnetic tape archives that were converted to use gold CDs in the past.

    The latest Blu-Ray gold archival discs could well be a long-term solution. Incidentally, if you hold some old aluminised CDs up to the light, you will see many holes. The aluminium is oxidised via seepage through the lacquer. Obviously, gold is far more resistant to this but the longevity of the medium would depend on the long-term stability of the DVD's base acrylic material and the coating lacquer in maintaining its transparency to the violet laser (the "Blu" ray) used to read the data. The digital encoding system does provide error protection against lost data bits but for how long it can cope with progressive deterioration, one can only speculate.

    For long term archiving, one should always review the latest archiving technology and also keep a regular check on the quality of the archived material. For valuable material, it is prudent to make several back-ups and store these in different locations, even using fire-proof and flood-proof safes if these can be justified.

    Sounds like an ideal business growth area to provide long-term secure data back-up facilities.
    17" MacBook Pro, Mac OS X (10.6.2)
  • Matti Haveri Level 6 Level 6 (8,840 points)
    It just means you have to render the audio. A bit of a pain


    Thanks for the info. I guess rendering audio is quite fast, so rendering 1 hour of audio shouldn't take very long (I plan to get a new Mac mini).

    I guess it is better to keep importing .dv with iMovie so I can preserve the embedded date in the timecode. Or does FCE keep that info when importing from tape to .mov? If yes, then I could import straight to FCE and keep exporting the edited material as .dv archive if I can keep the date info via that route.

    BTW, does FCE report dropped frames when importing from tape?
    PowerBook G4 1.25GHz 15 FW800, QT 7.6, iMovie HD 6.0.3, iDVD 6.0.4, Mac OS X (10.5.6), I don't benefit from any link
  • Alchroma Level 6 Level 6 (16,875 points)
    Audio rended from .dv is fairly quick but you'd be better using FCE for capture.
    Unfortunately you can't get the time data as you require.

    You may want to investiagte this:

    http://discussions.apple.com/click.jspa?searchID=-1&messageID=10740110

    Al
    Mac Pro 2.66 Quad, Mac OS X (10.5.6)

Actions

More Like This

  • Retrieving data ...

Bookmarked By (0)

Legend

  • This solved my question - 10 points
  • This helped me - 5 points
This site contains user submitted content, comments and opinions and is for informational purposes only. Apple disclaims any and all liability for the acts, omissions and conduct of any third parties in connection with or related to your use of the site. All postings and use of the content on this site are subject to the Apple Support Communities Terms of Use.