

Tuesday, January 11, 2011

Update on the reliability of flashdrives

Back in February I wrote about the reliability of flash drives. Because of their ever increasing capacity for storage, coupled with their convenient size, they have become the storage media of choice. But I still have the same questions as to how reliable are they? Are flash drives suitable for long term or archival storage? How do they stack up to other storage devices. Have there been any recent changes in the reliability?  Recently, in a discussion at the Mesa Regional Family History Center, two of my colleagues were discussing flash drives. I happened to mention the issue of read/write failure due to repeated usage since there is limit to the number of times you can write to a flash cell. One of the workers, said he had been in semiconductors his whole life and had never heard of such an issue. He simply did not believe me.

I recall the discussion surrounding the introduction and use of CDs and DVDs. They were originally claimed to have a storage life of more than ten years (or even longer). Adequate archive management cannot rely on the claims of manufacturers and anyone interested in long term storage needs to be assured that the storage figures are provable. In the case of CDs and DVDs the storage life turned out to be highly overrated. Here is an article on CD-R/DVD-R reliability

Flash drives instinctively appear to be almost perfect storage devices. They are portable, easy to use and work with almost all computers. But what is the downside? First of all their very portability makes them a rather unreliable storage media. They are very easily lost. At the Center we have a drawer dedicated to lost flash drives. Regularly, visitors to the Center forget their drives and leave them plugged into a computer. Unfortunately, those same people seldom have their name or contact information anywhere on the drive. It does not matter how reliable the storage device is physically, if it is lost.

Despite my friend's skepticism, flash drives really do have a limit to the number of times you can write to a flash cell sometimes called "write endurance." Manufacturers claims range from 100,000 writes per cell to over a million. These numbers may seem extraordinarily large, but if a flash drive is used for repeated changes to the same document (i.e. genealogy file) it can fail, just like the old floppy disks of years past. The real issue is something called the "hard error rate." The hard error rate can be reduced by software that spreads the read/write cycles over the entire flash drive rather than repeatedly using the same cells.

The engineering types seem to think that the longevity issue has been resolved and that flash drives will last over 50 years even with constant use. Right now, flash drives are not really in the running to replace hard drives. For casual users, they are a reliable solution, but right now the largest flash drives available are 256 GBs, which for my storage demands is way too small. They are also more expensive than hard drives for the same amount of storage. So as of the beginning of 2011, flash drives are a viable portable storage option, but as with every backup situation, use more than one type of storage in more than one location and certainly, don't put all your files on one flash drive.


  1. James,

    Thank you for confirming what I already suspected about flash drives. While I do have a couple of flash drives (one for school, one for work, and one for genealogy), I only use them if I know I won't have internet access or if I don't want to carry my laptop. I keep the majority of my files in multiple locations: my computer hard drive (or my laptop), an external hard drive, and my Dropbox. I also use Carbonite to back up both of my hard drives and my laptop. With all the "cloud storage" and other backup options, do you think there will continue to be a need for flash drives to be more than temporary?

  2. I use my flash drives to transfer data and that is about all. Never has been an option as a back up drive. That's me tho, you know the saying, each to his own.

  3. The problem of juggling multiple flash drives, coupled with the necessity of office storage prompted me to use and pay for our own wi-fi.

  4. Jenny
    I am interested in your comment about Carbonite. I use carbonite to back up my laptop--which I use as a desktop--but I ass/u/me d that I would have to have a separate subscription for my external hard drive.
    Do you?

  5. And - remember to always go through the "safely remove hardware" option when removing a flash drive. I only skipped that once and pulled the flash drive out. Bye bye flash drive. The computer wouldn't even recognize the drive again.

  6. When you talk about the flash drives are you referring to adding information or writing over the information you already have written?

    Seems like everything electronic has planned obsolescence. I think I will keep my paper records for now. But again I only have about 190 people.

  7. I've had two very good name brand flash drives fail so far. I use them often but only for transferring and would never rely on them for over time storage. External hard drives are great for extra storage as well as backups and Dropbox has worked flawlessly so far although it does cost for a larger amount of storage but is a great alternative or "in addition to" storage solution. I am just reluctant to trust any portable storage i.e. flash drives and DVD's at this point in time for long term storage.

  8. Thanks James, I know this is an old post but still it's valuable.