Hi Folks,

First of all, Since there are several thumb drives in the paper today, here is an article from Fred Langa about flash drive life span.

Life Expectancy Of Flash Drives?

Good morning, I would like to start by thanking you for the tremendous service you provide with your newsletter. I find items that are of both professional and personal value in every issue and I shall remain a Plus Subscriber until either you or I retire.
 
My question relates to thumb drive failure. I am aware that a thumb drive may only be written to a finite number of times. I would like to determine the nature of how a thumb drive fails when it reaches the end of its' life expectancy. I have been unable to craft a search string for Google that will yield information as to whether one might expect total, catastrophic failure wherein the entire device would become unreadable, or whether one might experience data corruption of individual files which might yield a clue that "the end is near".
 
Have you any tips as to how I might find information of this sort? As always, thank you for your time and for your excellent newsletter. ---David Chambers

There actually are several interrelated variables at play here, such as MTBF ("mean time between failures"), "expected write cycles," "data retention," and so on. If you can find the actual manufacturer of a flash drive (not necessarily the seller--- many consumer electronic devices are made by one company, then branded and sold by another...), you can look up the original specs, which often include detailed information.

You can think of MTBF as a rough guide to a mythical "average" unit's life expectancy as a whole. No, it's not really that simple--- what it really means is that half of all drives will have failed by the MTBF datum, and the other half will fail after that point. But in very crude terms, you can think of it as "average life expectancy" for the electronics. It's typically a very large number for solid-state devices--- I've seen some flash drives claim a raw MTBF of 1,000,000 hours--- that's 114 years! ( http://google.com/search?q=usb+flash+mtbf ) In any case, the basic electrical guts of a flash drive probably won't wear out in any reasonable time frame. But when it fails, it probably will be a total failure; it just won't work anymore.

Data retention is another variable: That's how long--- again, on average--- the device will retain its data in a usable, readable format, assuming it's just sitting on a shelf or in a drawer someplace, safe and powered off, and not subject to environmental extremes. Claims for this typically run to around 10 years. ( http://google.com/search?q=usb+flash+data+retention  ) That is, of course, a guess, because flash drives haven't been around that long. And even that seems long to me--- USB Flash drives simply aren't meant for long-term, archival storage. If you need to store data for a long time, I think CDRs or DVDs, suitably checked and re-recorded every few years, are a much safer choice. In any case, this kind of trouble could show up as gradual corruption of files; or as something worse if it's the master tables or boot records that decay.

And then there's the "write cycle" life you refer to. Reading data from solid-state memory is a lightweight event that places little stress on the components. But writing to Flash memory requires erasing what's there and re-recording new data; both of which involve higher energies. That's harder on the memory cells. Estimates vary, but many vendors seem OK with guaranteeing a conservative 10,000 write cycles or so; and some industry insiders say that the devices are actually good for about an order of magnitude or even two more than that--- perhaps as much as a million write cycles. (eg: http://en.wikipedia.org/wiki/Talk:USB_flash_drive ; http://google.com/search?q=usb+flash+write+cycle ) But when the drive "wears out" from rewrites, you could see anything from "soft" errors in individual files to a wholesale mangling of the master tables or boot records, depending on which data cells go bad, and in what quantity. There's no way to know in advance.

So what does this all boil down to? I suggest you treat Flash drives as short- and medium-term storage devices. They're relatively cheap and getting cheaper, so I don't think they're worth fussing over too much: If you're conservative about data-safety, plan on replacing the devices (or at least moving them out of front-line service) every two or three years. If you're more relaxed about data security, a 5-year replacement cycle is probably safe.

From the friday Fry's ad:

From the Friday's Fry's ad:

Front Page:

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Memorex 1Gig Travel Drive - $18 after rebates

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o rebates required
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100Pack CD-R $9

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Maxtor 500Gig Sata drive - $170

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They could be easy to loose though.

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More Next Friday,
Chuckstr
----My Web Site----

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