How long does Flash Data last (if drive is only used once)
April 1, 2011 10:40 AM   Subscribe

How long will data stored on a USB Flash drive last, if the drive is put away in storage?

I have about 60 GB of family photos, video, etc. that I want to back-up long term. I bought a 64GB USB flash drive (this one), copied the files, and put the drive into my fire safe. Assuming that I never read/write from the disk, how long can I expect the data to last?

Is there a better (non-online) solution?
posted by bagadonuts to Computers & Internet (12 answers total) 9 users marked this as a favorite
Well, two things - first, you really, really want to do this with a hard drive in an enclosure, not a USB key, and to keep the power and USB cables for the enclosure in the fire safe with it. Flash media is not a reliable long-term storage device.

Second, get all that data onto a second hard drive and keep it somewhere else, and make sure you spin them up every six months or so just to make sure. If you only have your data in one place, you won't have it at all soon.
posted by mhoye at 10:45 AM on April 1, 2011

No expert here, and I can't give you an estimate for time, but regardless of how long one flash drive lasts, if you have two, one can fail and still allow you to save all your files. Get another flash drive, load it with your files, and then store it in a separate location. Check them periodically, maybe every year or so.
posted by Homo economicus at 10:51 AM on April 1, 2011 [2 favorites]

That's about 14 DVD-R's worth of data, and premium line Taiyo Yuden media goes for about 36 to 41 cents each, so that's about six dollars worth of media. If this is data you really care about it's worth six bucks for the belt and suspenders approach.
posted by Rhomboid at 11:10 AM on April 1, 2011

I'm not convinced DVD-R has a longer archival lifespan than USB keys to begin with, but I suppose that's possible. They're also a lot more trouble to test regularly, and a whole lot more delicate.

I think the lifespan of flash storage (like USB keys) is usually measured in terms of (hundreds of thousands, or millions) of reads and writes, so if you did buy a new drive just for this purpose and wrote to it once to archive your data... and you check it every year or two... it should last a very long time, definitely more than 10 years.

To piggyback on econ's excellent suggestion: each year or two when you check, make a new copy onto whatever the current cheap media of the year is. 64Gb storage will be pennies in a few more years, after all, and you'll be able to carry it in your earring soon enough.
posted by rokusan at 11:15 AM on April 1, 2011

Yeah I would go with rokusans recommendation and copy the data over every year or so. Not only is storage getting cheaper but it could help avoid compatibility problems in the future. 10 years ago if you had put all your photos on a Iomeg Zip disk how easy would it be for you to recover today? (yes drives still exist but they are getting few and far between)
posted by Captain_Science at 11:19 AM on April 1, 2011 [1 favorite]

You can also look into something like parchive for error-correction, in case of corruption with individual files (ie, accidental deletion when reviewing or copying to new media)or file system fubars, etc.
posted by MikeKD at 11:29 AM on April 1, 2011

Just an FYI. DVD/CD-R media are recorded by light (laser) and so are vulnerable to ambient light degredation. Store in light-proof containers for increased longevity.

Those home movies that have been sitting in a clear container for 4 years? Might think about re-copying them to keep them "fresh".
posted by trinity8-director at 12:24 PM on April 1, 2011

The core of every flash ROM bit is a tiny capacitor. The difference between a "1" and a "0" is that in one of those the capacitor is discharged and in the other it has a charge. (I don't remember which is which, and it doesn't matter.)

The capacitor is well insulated, so the charge in it doesn't leak away. However, there is a slow tendency for the charge to dissipate as a result of exposure to environmental radiation, including cosmic rays.

All of which means that flash is not forever. It's hard to say exactly how long it will last, but likely a few years before bitrot sets in. It isn't permanent, in the sense of an eternal archive.

Optical disks are subject to a different kind of bitrot, and they're not eternal either. Again, they're good for years but not for decades.

A USB hard drive is a better choice, but that's not eternal either. There are yet other environmental factors which cause a slow rate of degradation.

In the end, the only way to be sure is to keep multiple copies, and to refresh them yearly.
posted by Chocolate Pickle at 1:20 PM on April 1, 2011 [1 favorite]

A solid state drive isn't going to store data for any good length of time, not in any catastrophe-avoidance plan. A USB hard drive with spinning platters isn't going to last very long, either; the moving parts degrade as well, even when not powered on.

So, finding a disk-based archive process is going to be the way to preserve your data. I'd even like to mention that Bluray data storage is getting pretty cheap, about what dual-layer DVD was a few years ago. I haven't heard anything about the longevity of writable Bluray disks, but it'll definitely be longer than solid-state storage and probably longer than a mothballed hard drive. Put into place an archive-rotation plan, multiple copies, reburned every so often, and your data will be more safe. One backup copy on any storage medium is better than none, but no guarantee of permanent digital storage.

I also don't particularly trust 'cloud' backups - you don't really have any control over how they avoid catastrophic data loss. I have no experience with them, though.
posted by AzraelBrown at 1:31 PM on April 1, 2011 [1 favorite]

Much of my early career was working in non-volatile memory like ROM & FLASH. In general these types of memories are tested to guarantee 10 years of data retention (This Kingston brochure suggests that 10 years is still the standard). In FLASH memory the data retention is definitely a function of use, so less use means longer data retention. It is also a function of temperature, keeping things at lower temps will slow down degradation.

That all said, the bigger issue in 10 or more years time will be finding a USB port an a computer that you can plug your drive into. USB 2.0 is already getting long in the tooth and I would predict USB 2.0 sockets will be rare on whatever tablet/phone/brain implant device we're using to interface with our AI overlords in 10 or more years. I also predict that optical CD/DVD/BR drives will be about as common then as floppy drives are today. So copying everything to new storage every couple of years is probably a better solution.
posted by Long Way To Go at 2:26 PM on April 1, 2011 [1 favorite]

No, USB doesn't look to be in trouble. USB 3 (5 gigabit) is approved and rolling out now, and it's backward compatible.

Yeah, eventually it will be as hard to connect to as RS-232 is today, but it'll be more than ten years before that happens.
posted by Chocolate Pickle at 3:47 PM on April 1, 2011

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