Disc life

[Martyn Hull]

BBC News - Click - 29 May
Most of us know this but its worth bearing in mind,having said that a random test of my first home made10 year old dvds burnt on a Pana recorder showed no failiers although i may well have missed THEM and i have had a couple lose info over the years.

[Jay West]

Am I missing something or is Firefox maybe keeping me from seeing something? When I click on the link, all I get is; (a) a Toyota commercial: (b) links to other BBC stories; and (c) a tag line about needing to worry about older CDs and DVDs.

[Martyn Hull]

Very strange as soon as i click on the link it starts the programn playing perfectly .

[Paul Mailath]

works fine for me - maybe it's the US corruption of the spelling that's causing the problem ;-)

[Dean Sensui]

I discovered a while back that CD's and DVD's don't last as long as people once thought. Even commercial CD's can fail.

Tapes can lose their oxide coating and be physically damaged, the same way that videotapes are destroyed.

I decided to archive on hard drives. They're fast, getting cheaper all the time, and can be mirrored. There are always two copies to protect against drive failure, and a third to protect against accidental erasure.

[Marcus Marchesseault]

Dean, have you put hard drives on the shelf for a few years and come back to them later? I have a friend who had several drives fail after about only a year on the shelf.

I will also back up that no laser disk/c media lasts forever. Hawaii is particularly debilitating to metals and some plastics. For instance, many speaker cones have their foam gasket around the cone just turn to dust. My guess is some sort of microorganism eats it. Salt spray and high humidity rust unprotected metal overnight. I've had factory-made CDs get a corrosion that looks a bit like a lightning bolt. It appears that some sort of nucleation site starts at the edge and randomly works its way through the aluminum making the lightning pattern.

[Jay West]

Well, my not seeing the story did turn out to be something in Firefox. IE took me right to the story.

To say the least, the reported research is cause for concern for archiving on optical media.

Not to say that archiving was of much concern to me until recently. As a one-man shop shooting most ephemeral things like school plays and weddings on limited budgets, I have been reluctant to invest in IT solutions like computer tape drives and archival hard drives. Plus, lot of my stock-footage collection was shot in much lower resolutions than the ones now available and are essentially obsolete. Much of the stuff I have to hand has not been worth what it would have cost me to archive it. DVDs and mini-DV tape seemed to have as long a life as I thought my work required.

Recently, however, I found some very inexpensive HP-branded USB drives ($49 US for 500 gB) at our local Costco) and have started using them to store additional archive copies of DVDs and finished projects. I started doing this for two reasons. One was to guard against computer crashes after loading tapeless-video from the new cameras. The other was that the hard drives make much easier and faster for me to retreive older files than what I'd otherise have to do, which is pawing through file-folders to get DVDs and then pull the video off the archived DVDs. (For instance, a parent might belatedly order another DVD of last year's school play or I might want excerpts from recent weddings when making a new demo DVD.)

I note that the reported tests of CDs and DVDs seemed to involve harsher treatment than would be expected with archived file copies of DVDs. As a check, I pulled some DVDs that I made ten years ago and had no trouble playing through them. That may have been mere luck or it may be because the discs had been stored in folders in a temperature stable environment (unlike the discs described in the testing in the story.) I've also got some 25 year old music CDs that I still played regularly, at least until recently. (I've lately started ripping them to mp3 or iTunes files and playing them that way.) So, archival life for digital disk media can be respectable if not guaranteed.

Another thing I like about the hard drive copies is that they are a lot more convenient than a stacks of optical disks for any periodic recopying.

[Dean Sensui]

Marcus...

Some of the drives I have on the shelf have been sitting there for the past five years and are still working fine.

There are about 50 drives on the shelves. They're IBM/Hitachi SATA drives, kept in an air-conditioned room. None have failed yet.

I buy bare drives and mount them in sleds. I'm using them in a Firmtek system.

[Martyn Hull]

Originally Posted by Marcus Marchesseault

Dean, have you put hard drives on the shelf for a few years and come back to them later? I have a friend who had several drives fail after about only a year on the shelf.

I will also back up that no laser disk/c media lasts forever. Hawaii is particularly debilitating to metals and some plastics. For instance, many speaker cones have their foam gasket around the cone just turn to dust. My guess is some sort of microorganism eats it. Salt spray and high humidity rust unprotected metal overnight. I've had factory-made CDs get a corrosion that looks a bit like a lightning bolt. It appears that some sort of nucleation site starts at the edge and randomly works its way through the aluminum making the lightning pattern.

You have jinxed me Marcus one of my externals will not show its content now,pc world in my town are currently trying to extract the content to put on a new drive but if they cant i still have it all on tapes but it will be a long job recapturing.Tape is still the most reliable storage as far a i am concerned, i have never lost info from any yet and i have analougue ones 30 and digital tapes 14 years old,drives and discs reliability leaves a lot to be desired.

[Marcus Marchesseault]

I have a hard drive sitting next to me that is making too many clicking sounds. I think it's going back to the store.

Hard drives are not made well anymore. My first hard drive cost $400 and lasted 15 years and multiple owners. I had given it away or sold it cheap years ago and it was then donated to a friend of mine. It had been through a flood. It still worked. This was an ancient Seagate RLL connector drive on an Atari ST and probably weighed 5 pounds. Right now, I'd take 5-pound hard drives that cost $400 if they were reliable again. I really don't like giving responsibility of a terabyte of data (76 hours of video) to a crappy drive made in a country that pays untrained/uneducated workers less money per day than I spend on snacks. I would buy SCSI drives if they weren't made in the same factory. I don't care about these 5-year warranties. The data is worth 10 times the price of the drive. Give me a one-year warranty and make the things last at least a year!

[Dean Sensui]

Are the drives that failed IBM/Hitachi drives? Or are they some other brand? Even the Seagate's haven't been especially reliable.

But as mentioned, the drives I use have proven themselves. The drives that have failed are external LaCie and Western Digital.

And, again as mentioned, I use mirrored RAIDs for archive, with an additional backup. All mechanical equipment are subject to fail, and the mirrored RAID ensures that in the event of a failure the RAID is still functioning.

Similar technology is used in critical systems including banks, air traffic control, etc.

[Martyn Hull]

Mine is a 4 year old Toshiba one, i am not sure if they are bad buys its the only one i have the rest are seagate etc,the pc store is getting the video from it but its costly and will end up costing £2.50 sterling an hour.

[Wesley Cardone]

If a CD or DVD fails to be read by a player you can probably still restore the disk by merely copying it to another disk. Even Tayo Uden DVDs are recorded with errors, though far fewer than your consumer grade media. There is sufficient information on the DVD or CD that the player can correct errors on the fly as then come down the pike. The player has only so much time to identify and correct errors in real time as the media is played for the viewer/listener. If it cannot do it in the alloted time it quits and complains that the disk is bad or skips. With age more and more errors appear on the media until there are finally too many. When you copy the disk there is no time limit to correct errors and you are therefore usually able to make a good copy from a bad one.

[Martyn Hull]

So using software like IMG BURN /SLY SOFT/ANY DVD will copy dvds that can not be read by standard players.Interesting

[Jim Andrada]

Despite all the claims, optical media have issues re archival storage, and it will only get worse as densities increase. There are a couple of ways to increase the storage capacity - multi layer (I've seen some proposals for up to 8 or 10 layer Blu-ray media) and/or smaller bit cells

Small cells translate into less power to drive the state change which in turn produces a need for media that require lower energy to effect the state chage, And this means that the media is less strongly resistant to the state shifting back - ie bit dropping.

Hard drives are basically engineered to spin, not to sit on a shelf, and if the drives are in some kind of array, good array firmware runs continuously scans the checksums and takes corrective action when it finds evidence of a bit drop. Of course, as soon as you take the drive out of the system and put it on the shelf, these checks are no longer being performed and bit drops can occur (often called "bit rot") and go undetected until there may be too many to recover from with normal error recovery.

Computer tape, (ie LTO) is engineered to sit on a shelf for years - there are (for example) special coatings front and back that prevent tightly would wraps of tape from sticking to itself over long time periods.

Nothing is perfect, but much as people wish it weren't so, serious tape is very hard to beat.