PDA

View Full Version : Technical: Long Term Storage Of Video files (Long Post)


BobDiaz
12-17-2007, 11:21 AM
Both the HVX-200 and the EX-1 users are going to face the issue of how to store their videos for the long term. Fortunately, this issue has come up before with large networks and the possible solutions are well known. The perfect solution doesn't exist, so users will need to decide which solution is best for their needs. This technical note addresses the choices and issues you will need to face when selecting your backup plan.

Removable Hard Drives:

Placing all your critical video files on a single hard drive is just plain stupid. Sooner of later the drive will fail and all your hard work will be gone. There are companies that do offer a recovery service for failed hard drives, but a better and less expensive way is found below.

The solution is to back up your videos onto 2, or better yet, 3 removable hard drives. If one drive fails, you can recover the data from the other drive(s). If you really want to be safe, store the other drive or drives at a different location or locations. The reduces the risk of a fire, flood, or some other unexpected event from destroying all your drives.

Another thing to consider is using multiple removable drives from different manufacturers. While the chance of purchasing a product with a manufacturing design flaw is small, getting product from different manufacturers reduces this possibility to near zero for every set of drives. So your first set of drives is from company "A" and your second copy is stored on drives from company "B". If you use a third copy, that would come from company "C".

Unfortunately, putting drives on a shelf for years at a time, without running them, may result in all the drives freezing up. This means that you'll need to go to all the drives to run a file check program once or twice a year to avoid this. As soon as one drive fails the file check program, you'll need to get new drives and make copies of the files from the good drive(s).

It's difficult to say exactly when one of your removable backup drives will fail, because they are only plugged in for backup and file verification. Three to five years is the normal life for a drive that receives regular use, but maybe with limited use, a drive like this may survive 7 years. However, a dropped drive is most likely dead as soon as it hits the floor.

Prices of USB and Firewire removable hard drives have dropped over the years and will continue to drop. As of today, the Mac Mall catalog shows a 2TB (2,000GB) My Book Pro Edition II selling for $639. Such a drive would hold over 100 hours of 35Mb/s material. That comes to under $6.40 per hour of material. The 500GB USB drive by LaCie sells for $118. Such a drive would hold over 25 hours of 35Mb/s material at under $5 per hour.

Just multiply the $6.40 or $5 by 2 or 3 to see what each hour of material would cost when placed on 2 or 3 drives and cost ranges from a low of $10 to high of under $20 per hour of material. Remember this covers you for a range of 3 to 7 years. After that, you'll need to get another set of drives to store the data. However, by then, the price per GB (or per hour) of material will be considerably less than today's price.

A sure bet is that in the future, even larger drives will appear at the same price as existing hard drives. Thus, in the future, when you move files to newer drives, you'll be able to move several "smaller drives" onto larger drives.


Optical:

In theory, optical media should have a life-span of 20 to 250 years.

http://www.techmount.com/index.php/20051205/dvd-lifespan/

Articles on CD and DVD Rot have placed a major shadow of doubt on whether optical media will last that long.

http://en.wikipedia.org/wiki/CD_rot

However, the correct answer depends on several factors that can't be judged by the average user.

http://www.larryjordan.biz/articles/lj_dvd_life.html

My suggestion here is, to stick to major name brand disks and if possible, select disks that say they are for archival and are of a higher quality. That may be a marketing trick, but it could also be a higher grade disk. The most important thing to do is to record the video files on several different brands of disks. Even in the worst case of all the disks getting rot, the chances of them starting to show rot at the same time is near zero. Remember you will need to test the disks every year by seeing if you can copy files into a system.

SL (Single Layer) DVDs are very inexpensive, but would only hold around 12 to 15 minutes of video per disk. DL (Double Layer) DVDs cost considerably more per GB, but could hold around 24 to 30 minutes of video. Because prices of the blank media vary so widely, the costs vary from about $1 to $6 per hour of material (one copy).

HD DVD would hold 15GB SL (>45 minutes) or 30GB DL (>90 minutes), but burners are just not practical yet. Blu-ray is a bit better with 25GB SL (>75 minutes) and 50GB DL (>150 minutes). The big question is whether either format will be around in the next 5 years?

There is a chance that both formats could die in the format war and who knows, maybe an even larger capacity optical media will take over. While many pretend to act like they know how the format war will end, chances are we won't know a clear cut winner or looser of this war until 2009 or 2010. By then, if one or both of the formats wins, it should be a reasonable long term solution.

With Blu-ray optical storage, SL 25GB disks sell for around $14 to $30 and DL 50GB disks sell for around $50 to $60. That comes to around $11 to $24 per hour for Blu-ray (one copy). However over time, the price for blank media will drop.

If you can find an HD DVD burner, blank SL 15GB Disks sell for around $12 to $15. That comes to around $16 to $25 per hour (one copy). However, over time, these prices will drop.


Back-Up Tape:

This seems somewhat odd to talk about "going tapeless" by copying all your video data to tape. However, backup tape systems can store large amounts of data rather cheaply. Depending on who's system you chose, the price can range from under $2 to over $5 per hour of video (one copy).

Some warnings on tape are needed; ALWAYS VERIFY ANY DATA YOU WRITE TO TAPE!!!!!! There are horror stories of people who backed up the server data every night onto tape, but failed to verify the data after it was written. It turns out that the tape drive went through all the motions, but recorded garbage to the tape. It was only after a major hard drive crash that the person discovered that all the backups were worthless.

Also, the estimate of tape's life-span is about 10 to 30 years. The worst problem is that tape drives change so quickly, that unless you have 2 or better yet 3 identical tape drives, you might not be able to read the tapes when the drive dies. Plus, getting a replacement drive that can read the tape may be next to impossible.


Storage While Out In The Field:

Storing your files to a laptop's hard drive seems reasonable, BUT I wouldn't want to have the drive of the laptop be my only storage location. One drop could quickly loose weeks of work. Having a second or third copy on a USB Powered drive(s) would provide additional protection.

One interesting idea I read on one of the forums was to use the 8GB, 16GB, or 32GB USB Flash Drives to back up your files while in the field. You can now find 8GB Flash drives for under $100 and 16GB Flash drives for under $200. The 32GB Flash drives sell for around $300 to $500. You can expect that over the years, these prices will drop.

Compared to the cost of the SxS cards, these flash drives are only a fraction of the cost. They are not as fast as the SxS cards, but they may be fast enough to copy all the files during the breaks between shooting.

Compared to the cost of a USB Powered Hard Drive, the USB Flash Drives cost about 10x more per GB. Unlike hard drives, USB Flash Drives can be dropped without any real problem. Anyone one going with USB Flash Drives is paying more to have the extra protection. Still, I never like to work with just a single copy of my files. So, even with Flash Drive Storage, having a second backup on a Hard Drive is still a good idea.


Bob Diaz

naveenmedia
12-21-2007, 09:54 AM
Thanks Bob. We're dealing with that issue now. At the moment, we're archiving to Raid 0 twice, creating a set of redundant back-ups in case of any HDD failure. We're also still considering tape, but with HD files the amount of tape required could get cumbersome, and tape formats are constantly changing.

For the time being, I think we'll stick to two Raid 0 back-ups, plus archiving finished pieces to the highest end digital tape we have available (as well as HDD).

Naveen

ullanta
12-21-2007, 11:37 AM
With the simplest of extensions to currently available products, I think the following is an ideal and fairlly futureproof solution:

Archive to the currently cheapest optical media (currently 1-layer DVD). Include in each archival volume a special metadata file describing the contents, which is also used to generate what's printed on the surface of the disc. Every year or so, toss the discs in a duplicator (or bring your stack of discs to a service) and "refresh" them.

When new optical media becomes available, a special duplicator (or service) can take your stack of discs and compile them onto a smaller number of "new media" (e.g., putting five DVDs onto a Blu-Ray), using the metadata to generate new labels and such.

An initial alternative for those of us who already have large archives without these metadata files is for someone (I've tried to push this idea on a number of manufacturers - no dice so far!) to build a duplicating machine with an integrated camera/scanner. It will take a stack of discs and duplicate it, printing a copy of the surface of each disc on the new copy. In "mixdown to new media" (e.g., 5 DVD->1 Blu-Ray), it might print smaller copies of each disc surface, and save full-size images on the "compilation" disc as part of the metadata.

The great benefit of the latest trends in optical media (CD, DVD, HD/Blu-Ray) is that the form factor remains the same and drives tend to be backward-compatible; and the media is very suitable for such automatic handling. Since media capacities will likely continue improving, this type of "plan to refresh archives" seems more reasonable than trying to get the longest-lasting archives. We have way too much media around now for which we no longer have playback capability!

naveenmedia
12-21-2007, 07:12 PM
I dunno ullanta, each 1-layer DVD is 4.7 GB max. That's a lot of DVDs, especially once HD gets in the picture.

BobDiaz
12-21-2007, 08:54 PM
This is a problem where one solution won't fit everyone's needs. The SL DVDs are OK if you don't have a ton of video to save. A 16GB SxS card would require 4 SL DVDs. If you want a second copy on DVDs, that comes to 8 SL DVDs. If you have 12 hours of video to save, assume a 16GB SxS holds 60 minutes of video, that comes to 48 DVDs (one copy) and 96 DVDs (2 copies). Not impossible, but a lot of work to copy.

USB or Firewire Hard Drives could hold hours of footage, BUT one must have at least 2 exact copies of every file on two separate drives. I do NOT consider these drives a long term solution, because every 3 to 7 years, the files would need to be copied onto a new drive. Not impossible, but as the footage adds up, this could be a lot of work. I consider this solution a way to buy time for the HD DVD/Blu-ray format war to be resolved. In 3 to 7 years, we'll know which format will be around for a while.

Even then, when something new replaces that format, it's a matter of copying the existing files onto the newer, up to date format while you still have the hardware to read the old storage system.



Bob Diaz

ullanta
12-21-2007, 10:33 PM
Yes, a lot of DVDs! I'm not arguing that! i DO have a ton of video to save and it's a pain in the butt. But when Blu-ray discs are cheaper you can quickly take advantage, and have a simple migration path. I'm not saying it's great, but the whole point is that is is NOT "a lot of work to copy." You put a stack of discs in the duplicator and hit "go"... for either copying, or migrating to new media.

Sure, the number of DVDs sucks now; but I haven't found a better, more reliable solution. I HAVE had a lot of cheap HDs die on me.... A good tape drive is agood option, but much pricier, and doesn't (at any level near what most of us could afford) allow for automated copying/migration of an entire tape library...

boredoftherings
12-22-2007, 04:44 PM
What about Sony Professional discs? Apparently they are just blue-ray discs in special cases, but they are supposed to last up to 50 years. As soon as Sony updates the firmware of the PDW-U1 to be able to burn 1920x1080 footage, will not that be the archival solution par excellence?

ullanta
12-23-2007, 01:20 AM
How much money (for equipment and per disc)? It seems to me like something pricier than the indie-range could afford...

Postmaster
12-23-2007, 02:17 AM
Let s face it. If you want to conserve information for a long time you need clay tablets or carve it in stone. Information was saved for over 6000 years that way and is stil avialable. :thumbsup:

The next best thing is film. It lasts maybe 100 years when stored correct.

Every kind of optical/tape media is suspect.

Remeber the Syquest cardridges?
If you are able to find a drive, does your computer have the old scasi 1 plug?

So you need a old scasi card. Will it fit in a pci slot? Noooo!

So you need an old computer, and vintage driver (good luck)
and a vintage OS that can talk to the driver but can not handle that large
file formates and so on......

If you pulled the files you find them in a compression format, that is not longer supported caus they used a capture card of a company that went broke/got merged 10 years ago.

the story goes on for weeks just to find out that the data is corrupted anyways.

Don t ask me how I found out that. :-BlackEye(DBG

Having a stack of disks and copying the data to a new set every 5 years sounds the best alternative in the moment. Having them in a format like Targa resolves the codec problem for a while but results in huge data.

Even if you loose some material over time, it probably does not mather because in 15 years nobody want to see that lousy low res 1920x1080 material anyways.

Would you mind to find out that your 1985 VHS tape of Star Wars lost so much magnetism that you cant watch it anymore? (if you still have a VHS player - do you?)

We entering a century where everyone and his kid brother produce more video from cellphone to Viper than ever. But we also entering a century of global amnesia. In 200 years we will have more stored information from the sumerians than of the year 2007.

Frank

ullanta
12-23-2007, 03:18 AM
If the automated "refresh" process has decent metadata, than codec conversions could be performed during the same process to keep them updated...

BobDiaz
12-23-2007, 07:43 PM
Postmaster brings up some good points, so let me answer them...

The media changes over time, i saved a few 8" floppies just for fun, but have nothing to read them with.

However, there is a period of time where the media is in transition. Where one can copy from old media to new media. For example, some of my older files were copied from 5 1/4" disks --> 3.5" disks --> ZIP Disks --> CD. The more popular the media, the longer it will be supported.


The file format will change over time and no longer be supported.

Also, true, but like the hardware, there is a time where both the old and new formats are supported. My best guess is that in 10 years Flash Memory will be around 32 to 128 times larger than today. Even with a minimum increase, why record at 35Mb/s? It seems logical to use a higher data rate, like 350Mb/s and have greater bit depth and color depth.

So what happens to the old format? Well, you could go to Final Cut Pro, version 999 and convert it one file at a time, but there will be a big market for those who want to translate lots of files to the new format. I can see someone, like David Newman, seeing the market and offering such a product. (Not that David Newman will be the one to offer it, but someone will. On the other hand, David has offered some cool stuff to the market, so he may do it some day...)


If something is so important, you don't ever want to loose it, copy the files onto several different formats; Optical, Hard Drive, and Tape. Also, save it in several different formats on each media. That way, the chances of something making it to the future is increased.


Bob Diaz