USB flash drive: 10-year memory retention?

I recently purchased a Memorex 256MB USB flash drive, also known as a thumb drive. The package lists all the wonderful things about the device and has this line, bolding mine:

“Compact, lightweight and durable 10 years of data retention

Question the first: Why only ten years? A search of past SD threads reveals mention of flash memory’s finite life span, measured in ‘write cycles.’ Is this what the 10 years of data retention is referring to?

Question the second: Are those 10 archival years, or 10 usage years? That is, if I save something to the thumb drive today then bury it in my sock drawer until 2013, will the data suddenly disappear or become unreadable at that time? Or does it mean that I can expect about a decade of regular use out of it? Will less frequent use yield a longer life span?

Question the third: What form will the 10-year failure come in? Will it be catastrophic, or will I see a slow degradation of storage ability that suggests it’s time to get a new device?

(I realize, of course, that with the rapid pace of technological change, the question is rendered somewhat moot. A decade from now USB flash memory thumb drives will surely seem as quaint as 5.25-inch floppies do today.)

A day later, is there no Doper among you who’ll rescue me from my ignorance?


Maybe even a joke or a funny anecdote? I’m feeling real lonely here…

Two days and not even handy has a response?!?

Could someone just verify that I exist, please?

I think the bottom line is nobody knows. The technology is relatively new. When I worked in product development we would have to come up with futuristic predictions based upon what existing research there was. Based upon what I know about chip technology I would expect that eventually you wouldn’t be able to see any of the data on the chip through your USB interface. Usage probably has no effect on it, though excessive heat would probably fry it, ie. when using your laptop with your thumb drive on the beach in Maui, make sure to keep the thumb drive out of long periods of exposure to direct sun.


[handy response]Call your local computer store and ask them.[/handy response]

I used to be an engineer in the hard disk drive industry. I will make my best guesses to your questions.

The 10 year retention is probably “normal use” which includes some reading and writing and some storage. I would expect that they mean that you will start to see some degredation in a minimum 10 years but not a complete catastrophic failure.

They typically test things using “accelerated life testing” which includes doing millions of read/writes over many hundreds of hours and also testing under extreme environmental conditions (temperature, humidity, mechanical shock…).


** mbacko1 **, welcome to the boards! I suspect you’re right about no one knowing for certain yet due to its relatively nascent status.

So how long has flash memory technology been around?
hajario, thank you. In the absence of an engineer in the flash drive industry, I’ll take one from the hard drive sector. Thanks for your insights. And in order to stay in the spirit of the GQ forum, let me just say that both parts of your answer were spot on.

Am I right in saying that ‘flash’ is just the modern word for EEPROM (Electrically Eraseable Programmable Read-Only Memory)?

Mangetout you are mostly correct. In the old days what separated flash from eeproms was eeproms you erased only small sections like a word or 2 at a time. Erase time is significantly longer than programming time which in turn is significantly longer than read time. So erasing an eeprom some time took to long. So people came up with flash which let you erase large sections in the same time it took to erase small sections. There have been lots of advances in flash spurred mostly by the cell phone industry.

As for some answers to the OP. 10 years probably refers to how long the data will reliably remain viable after programming. If you write over the data the 10 year clock starts again. It will probably fail by having the 0s get erased by having the captive charge leak out turning the bits from 0 to 1.

Flash also has a limited number of erase cycles that can be performed. I don’t know what the limit is now but is it probably on the order of 1,000,000 or so.

As is often the case how stuff works has good info on flash.

The 10 years is an industry standard minimum, not a real calculated number. It’s just what the memory manufacture is willing to guarantee - the actual number is probably much higher. So those who quote it as “up to 10 years” are probably killing the engineers who made the chips. It also should be for the upper end of the operating range, which is rather high in human terms, 85 C or so. It scales by temperature, so at more normal ones like 25 C, it will last much longer. In fact, that is how they measure the value in the first place, by baking the chip at even higher temperatures, 250 C or so (look up “data retention bake” for more).

Interesting PDF on how Motorola calculates the number

Another PDF listing the failure modes for EEPROMS