One of the things I was struck by a couple weeks ago in my graduate systems course is how fragile data is. It’s interesting how a lot of people seem to think that digital is a safer or more durable format than film, when it’s most often the other way around. Once you shoot and develop a roll of film, the physical degradation your film strip will experience over the years (if stored properly) is nothing compared to the digital degradation of your digital files.
The general, technical term for this is bit rot.
Floppy disk and magnetic tape storage may experience bit rot as bits lose magnetic orientation, and in warm, humid conditions these media are prone to literally rot. In optical discs such as CDs and DVDs the breakdown of the material onto which the data is stored may cause bit rot. This can be mitigated by storing disks in a dark, cool location with low humidity. Archival quality disks are also available. Old punch cards and punched tape may also experience literal rotting.
Here’s what it can do to your digital photographs:
Personally, I backup each of my photographs twice – one on an external hard drive and one on a DVD-R. This definitely isn’t enough for long term data backup, so I’m going to have to rethink how I backup my data very soon.
In general, preserving digital data is a very difficult issue, even for companies with large amounts of money and resources. The fact is that nothing lasts forever (except souls, of course. Email me for more on that), and the challenge is mainly how to extend the life of our data as long as possible.
So what options do we ordinary folk have for backing up digital work? What steps can we take to make it more likely that our photos will be around in 10, 50, or 100 years?
Manufacturers claim that their high quality CD-Rs and DVD-Rs can last between 50 and 100 years, but this is assuming you buy the most expensive disks and store them flawlessly. Most experts estimate that your CD-Rs have a conservative lifespan of 6+ years and DVD-Rs 15+ years. Even then you’ll need a bit of luck.
The truth is, most of our discs won’t last very long due to a plethora of factors. First off, most of us are probably more cost-conscious than “data-longevity conscious”. We don’t always buy the highest quality disks to burn on.
Second, we don’t always store data properly. Improper storage or handling leads to disc rot.
Third, we’re generally time-conscious as well, so we don’t always burn our disks on the slowest, and safest, speed.
Here are some steps you can take to extend the life of your optical disks:
- Quality: Purchase the highest quality disks you can
- Burning: Burn your disks on the slowest burn speed for optimal data integrity
- Storing: Store your disks in jewel cases in a dark place at room temperature away from light and heat sources
- Handling: Be sure to take good care of your disks. Avoid touching the bottom or trying to clean them if possible. If text printed on a piece of paper is ripped or fades, you can still read it. If your disk gets a bad scratch, it could be rendered completely unreadable.
- Labeling: Don’t label your disks with adhesive labels or permanent markers
- Maintaining: If you’re seriously paranoid, you might want to transfer the data to new disks periodically, accepting the potential data degradation introduced in the transfer in order to avoid the physical degradation of the disks.
It’s not uncommon for hard drives to fail after a few years. Most manufacturer warranties are around 3-5 years.
First, let’s talk about the hard drives in your computer. Generally, drives last long when they’re constantly running at a steady pace. A computer that is always on will likely last longer than a computer that is turned on and off multiple times a day.
Also, in addition to the mechanical parts of a hard drive failing, the magnetic bit strength of a hard drive slowly fades over time, leading to data loss.
A possible way to play it safer when it comes to hard drives is to store the same data on different drives (increasing redundancy), since it’s unlikely that both will fail at the same time. Thus, if one fails, you can quickly get a new one and copy it over.
This is the general idea behind RAID, a popular technology developed by another professor here at Cal. There’s different levels of RAID, but the duplication strategy I just described (RAID 1) is probably the most applicable for consumers. The other RAID levels are more applicable for companies who want redundancy but don’t want double of every bit of data (no pun intended). You can buy external hard drives with RAID technology now, or you can just purchase multiple hard drives and do the mirroring yourself.
Some hard drive tips:
- Purchasing: Buy high quality hard drives. Saving money by buying large cheap disks isn’t a good idea, since you’re most likely trading more space for less reliability. What’s the point of storing more data if you’re much more likely to lose it?
- Handling: Sudden movements or shocks to hard drives can mean death to your data, especially when the hard drive is starting up. Keep the drive safe and stable.
- Maintaining: As I said earlier, the data on hard drives slowly “rots” over time. To prevent this rot you should periodically read everything on the
If you want to ensure that your grandchildren will see a certain photograph, the best option might be to make prints of it. While a print at your local drug store might only last 10 or 15 years before it starts to break down, a high quality print could last your lifetime. Here are some tips:
- Ink and Paper: The physical components that go into making a print are of utmost importance. Do some research and make sure you choose materials that last.
- Archival Materials: What you choose to display or store your photographs in has a big impact on the longevity of your prints. They need to be “chemically inert”, meaning they won’t cause the material in your print to break down.
- Location: Store your photographs in a cool, dry, and dark place. Heat, humidity, and light all cause the materials in prints to break down. If you hang your photos somewhere, avoid direct sunlight, since it will fade your photographs.
- Handling: Avoid touching the surface of your prints, since your fingers obviously aren’t chemically inert.
Cloud computing is becoming a pretty big deal, and many people have already entrusted other forms of data to big players such as Amazon or Google. In fact, services like SmugMug and Twitter trust Amazon’s S3 storage service so much that their images are all stored there. The question is, should you?
In generally, it’s probably safer to entrust your images to Amazon than it is to back them up yourself. I’m not exactly sure how services like Amazon deal with data corruption, but they have professionals dealing with the integrity of their data, while you’re most likely not one. The most common reason for data loss is human error, so in this regard, you’re much safer with Amazon than handing external hard drives yourself. In terms of price, it’s not so bad either.
The most durable way to store information is physically, not digitally. Here’s an interesting quote that I came across in this New York Times article about data rot:
Making lots of backups is good advice, and on different formats, different places; consider paper as an archival medium. Some paper we have has lasted thousands of years. If Moses had gotten the Ten Commandments on a floppy disk, it would never have made it to today.
Personally, I think the safest ways to preserve photos are with companies like Amazon for all your data, and by making prints for individual photos.
Have other tips? Leave a comment sharing them with us and I might add them to this post!