Re: Do bootable USB sticks have a date of expiry?

Michael <[email protected]> Tue, 18 Aug 2026 11:07:27 +0100
Newsgroups	gmane.linux.gentoo.user
Message-ID	<[email protected]>
On Tuesday, 18 August 2026 02:00:15 British Summer Time Dale wrote:
> On 8/17/26 10:29 AM, David Bryant wrote:
> > On 8/17/26 10:12 AM, Dr Rainer Woitok wrote:
> >> Greetings,
> >> 
> >> less than a year back I updated my bootable USB stick with the then
> >> cur- rent ISO image.   However, a few weeks back  I wanted to use
> >> it,  and it did NOT boot.   I had to first copy  a new ISO image 
> >> onto the USB stick using another computer.  Is this normal?
> >> 
> >> Sincerely,
> >> 
> >>     Rainer
> > 
> > It's not necessarily normal. But it's not unusual. A USB stick uses
> > quantum effects in semiconducting material to create regions of
> > trapped electrical charge that represent ones and zeroes. Over time
> > the trapped charge leaks out / gets shorted to ground. A good
> > quality USB stick should be readable for several years. A cheap one
> > might start "forgetting" things in six or eight months. YMMV.
> > 
> > --
> > D. Bryant
> > Canyon Lake, Texas
> 
> Questions.  What should a person do to prevent this from happening?
> Plug the USB stick in on occasion for a few minutes, so it can
> 'recharge'?? Should one do something else to prevent this?  Should
> one mount the file system?  Do something to the files to make them
> rewrite?
> 
> The reason I ask, I store backup data on m.2 sticks, USB sticks and
> such so that if I have a system crash, they would be much needed and
> quickly.  I store them in a fire safe.  I usually only plug them up
> when I need to update them.  Since I store things like the world
> file, passwords that I rarely change, they are not plugged up very
> often. That said, I also use USB sticks for bootable ISOs as well,
> like the OP does to it seems.  Those can sit untouched for a while.
> 
> Just curious if there is a way to prevent this.
> 
> Dale
> 
> :-)  :-)

I've experienced loss of files on USB sticks both with FAT and with 
exFAT filesystems.  The directory/file was listed, but I could not open 
it or copy it.  Using fsck, app-admin/testdisk and sys-fs/ddrescue 
didn't help.  Thankfully, the data loss was not critical, but it is 
annoying all the same.

Generally, M.2/SSD drives and comparatively cheaper USB flash drives do 
not have the same quality of memory cells and definitely do not have the 
same quality of flash controllers.

I read some tests which showed cheap USB/SD/microSD sticks where their 
unsophisticated memory controller performs virtually no wear levelling.  
Really cheap (smaller and older?) USB/SD/microSD sticks have no onboard 
controller at all and rely on the host OS accessing directly raw cells 
on them.  These won't last long and age quickly if overwritten multiple 
times.  Filesystems like F2FS are meant to compensate somewhat for lack 
of a device controller, but with no wear levelling or garbage collection 
the devices can't last if being written to frequently.

In addition, we have SLC, MLC, TLC and QLC NAND cell density 
technologies, storing increasingly more bits per cell.  All things being 
equal industrial grade SLC SSDs will last longer than discount unbranded 
QLC equipped drives.  This multilevel bit storage is not dissimilar in 
principle to CMR Vs SMR spinning drives and their respective longevity.  
Either way, charge leakage from a cell will eventually and inevitably 
lead to loss of data and file corruption.  When this moment arrives with 
SLC the loss of data will be more limited than with e.g. QLC.  This is 
why such media are not meant for long term storage and they cannot be 
trusted with important data without a higher fidelity backup.

I have read plugging in a USB stick will refresh the charge on the 
device and that should prolong its useful life.  Applying power will 
refresh the charge on the controller and this will help to maintain/
refresh its flash translation layer (FTL), but I am not sure the charge 
on each flash cell will be refreshed, unless such individual cells are 
re-written.  Plugging in a USB/SSD drive and leaving it connected is 
still a good idea, because it will allow for its flash controller to 
perform garbage collection while sitting there idle.  While it does this 
it may move cells around and this ought to help in part with data 
retention.

I've had USB sticks which lasted more than 15 years, but they were used 
occasionally and only for data transfer/short term storage.  I don't 
think they would have survived more than 5 years if used daily.  I've 
had SSD drives in daily use which lasted just over 10 years, before the 
controller died suddenly and all data became inaccessible.

Besides anecdotal data survival stories, I consider SSDs to be better 
than USB sticks.  Spinning (CMR) drives better than NAND cells.  Paper 
records in a fireproof box are better than magnetic disks.  The 3-2-1 
backup strategy applies and of course today we also have cloud storage 
(if you can trust them with your data).
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