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Old 04-29-2014, 04:16 PM   #1
maples
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Missing capacity on flash drives


A few months ago, I got a SanDisk Cruzer Glide 16GB flash drive. Both Windows and Gparted showed 16GB. I played around with the partitions, and a few weeks later I noticed the capacity listed under Gparted was about 14GB. That number hasn't changed from there, but I also have an "8" GB flash drive that from the moment I got it I only had 7.5 GB. I was wondering if anyone else has experienced this, and if anyone knows if that space can be re-claimed.

Thanks!
 
Old 04-29-2014, 04:19 PM   #2
szboardstretcher
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You lose some of the space due to the filesystem metadata, superblocks and file allocation table depending on the type of filesystem you are using. As the drive gets bigger, the more you will lose, due to this requirement.
 
Old 04-29-2014, 04:53 PM   #3
suicidaleggroll
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Quote:
Originally Posted by szboardstretcher View Post
You lose some of the space due to the filesystem metadata, superblocks and file allocation table depending on the type of filesystem you are using. As the drive gets bigger, the more you will lose, due to this requirement.
In my experience, it's typically about 8-10% that you "lose".

This is the case with all drives, all interfaces, all formats, all operating systems.
 
Old 04-29-2014, 05:03 PM   #4
szboardstretcher
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Correct. Also, manufacturers don't seem to be required to call out the correct size. A "200GB" western digital, raw and unformatted actually has 186G of space.

I'm unsure whether this is true of Flash drives as well.
 
Old 04-29-2014, 06:20 PM   #5
TobiSGD
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(Flash-)Disk manufacturers measure a GB as 1000MB, a MB a 1000KB, and a KB as 1000 bytes, while your OS measures a GB as 1024MB, a MB as 1024KB and a KB as 1024 bytes. So the discrepancy is solely a matter of which units are used.
Since kilo, mega, ... in normal non-IT measurements default to a factor of 1000 it was defined that is is now the case also for measurements in IT, while units with a factor of 1024 got an exchanged syllable bi, for example Gibibyte.

Last edited by TobiSGD; 04-29-2014 at 06:22 PM.
 
Old 04-29-2014, 08:47 PM   #6
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Using GB to GiB conversion the 16 GB should show as 14.9 GiB and the 8 GB as 7.45 GiB.
 
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Old 04-29-2014, 09:12 PM   #7
jefro
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If gparted does show no free space then I'd assume all is full.

To be sure, use the chs to see if it adds up to what it is supposed to be.
 
Old 04-29-2014, 09:22 PM   #8
Emerson
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BTW, there is no unit like KB (Kelvin-byte), it has been made up by illiterate people who do not understand SI is case sensitive. http://physics.nist.gov/cuu/Units/binary.html
 
Old 04-30-2014, 04:52 PM   #9
maples
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Quote:
Originally Posted by metaschima View Post
Using GB to GiB conversion the 16 GB should show as 14.9 GiB and the 8 GB as 7.45 GiB.
That sounds about right...Thanks! I thought when I origianlly got it, Gparted said 16GB, but I must have been wrong. It wouldn't be the first time...
 
  


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