I’ve always wondered how long a flash drive would last, and so, I’ve decided to do some research on the subject and share it with everyone. First, let’s clarify the question as there really are two parts to it, and I’d like to examine both:

1. How many times can you write to a flash drive before it stops working?
2. How long will a flash drive retain its data?

Wikipedia tries to answer both questions with a simple statement: “Some allow 1 million write or erase cycles and have a 10 year data retention cycle.”

That’s sounds overly simplistic. Let’s address each part of the question and see what we can learn:

#1 How many times can you write to a flash drive before it stops working?

Wikipedia’s footnotes on the same USB flash drive page mentioned above state: “USB flash drives allow reading, writing, and erasing of data, with some allowing 1 million write/erase cycles in each cell of memory: if 100 uses per day, 1 million cycles could span 10,000 days or over 27 years. Some devices level the usage by auto-shifting activity to underused sections of memory.”

I’ve seen some companies’ descriptions of flash drives with the read/write limit varying from 10,000 to 1 million. Why? While there are some variations in flash memory cells, most likely some are referring to the older way of describing read/write which related to any particular cell. However, things have changed with the newer, higher quality flash drives. Due to the auto-shifting activity mentioned in the Wikipedia article (or “wear leveling” as described by Michael Yang, flash marketing manager for Samsung, in his early 2008 defense of flash memory for use in computers), a flash device that is rated 10,000 write cycles can write 10,000 times to every single flash memory cell in the device. A flash device can then rotate which memory cells are written to and redirect the “read stream” of data to good cells in the event some cells become defective.

Here’s an interesting article on the Japanese scientists who engineered new flash drives that can last virtually indefinitely through flash drive wear leveling. With automatic “wear leveling,” you then could theoretically write to a newer, premium flash drive day in and day out for years before the drive “dies.”

And, in terms of flash drive death, as Josh Bressers writes based on his study, writing 90,593,104 times to a flash drive with the intention of making it die, flash drive death only means one thing -  you can no longer write to it, but you can still read data from it.

BitMicro has a helpful press release in defense of flash memory. Of special interest is the “Longevity/Lifespan” section which mentions that “currently the best flash chips are rated at 1,000,000 write cycles per block (with 8,000 blocks per chip).”

#2 How long will a flash drive retain its data?

The second facet of the question is also a crucial one that many people have asked. Most of us have heard that flash drives can only retain data for so long even without a couple million read/writes.

In regard to this question, Ben Hodgens, on Josh Bressers’ post mentioned above, writes: “It’s hard to say how long a flash drive will ‘last.’ It’s going to be subject to the same electro/magnetic deterioration any other electronic or magnetic media is subject to: over time, the cells will lose their charge state, resulting in the discreet 1s and 0s being muddled.”

I haven’t been able to find much information on gradual memory loss in flash drives. Wikipedia does have an article on bit rot which briefly mentions flash drives. As Ben Hodgens mentions in the above referenced article, “we’ve not had flash drives long enough to  make a concrete determination.” As with any form of memory which relies on electro/magnetic charges, inevitably, decay will happen.

Though flash drives are superb for <10 years short term archival (like the floppy disks of yesterday or even magnetic tapes, CDs, and DVDs), they are finite in their endurance. While Japanese scientists exercise their brains to develop methods to ensure continued longetivity with flash drives, you can rest assured that a quality flash drive will provide you with meaningful, valuable use during the oft quoted 10 years of its reliable life; however, as with any other form of technology, don't use them for single source archival and be sure to upgrade to larger, newer devices every couple of years. Right now, it's easy to do that as the memory capacity for flash drives continues to increase (and prices for higher capacity drives become more affordable). If you have crucial data, don't just set it on the shelf archived forever; store it on the latest technology and continually upgrade to be sure you'll be able to have continued access as your technology changes. What would you do if you'd locked away all your important data on relatively obsolete 5 1/4 inch floppy disks? After all, we've been upgrading what we use to store data on all along for the past couple of decades, mostly subconsciously probably: floppy disks, CDs, DVDS, flash drives, and the list will only continue.

And so, in summary, thanks to the continued improvements in USB flash drive technology, flash drives are becoming better and better with longer lifetimes and increased reliability. While there are some limitations, as with any technology, flash drives remain an incredible investment and an easy, portable tool that tens of millions worldwide (including me, and probably you too) use every day. It's because of this that we, at CFgear, push custom flash drives as an ideal promotional tool for businesses, schools and nonprofits. But don’t just take our word for it – give it an honest try and see what you think.