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First regular Hard Drives (spinning disks):

When looking details of a brand new hard drives, I've noticed that the available space usually ends with xxx,000,000,000

For example, a 750 GB drive is usually at least 750,000,000,000 bytes. Maybe a few extra bytes. In other words, 750*1000*1000*1000 (not 1024 multiples).

The operating system calculates by dividing by 1024 multiple times. Upon dividing 750,000,000,000 bytes by 1024 ^ 3 the result is 698.49 GB (which is what I would expect my Operating system to display as the actual size of the drive due to this "1024 based sizing math").

Now onto USB Flash drives:

So, when I connect a brand new USB flash drive should I also correctly expect to see (in the case of a 64 GB size) 64,000,000,000 bytes for the overall size of the drive? (on a couple brand new flash drives I'm seeing considerably less which is why I'm asking this question)

Regarding internal USB flash drive maintenance:

Over time, when you use a flash based storage device, I've come to the understanding the drive will do internal maintenance (wear leveling, etc). But, I'm trying to determine if the extent of missing sectors that I'm seeing is normal on a couple of brand new flash drives. One is missing over 700 MB and the other is missing over 5.2 GB

Does that mean that the overall amount of sectors available to the Operating system or partitioning tools shrinks over time as sectors are removed from availability (due to being marked bad, etc)?

BACKGROUND: When discussing storage space size, many people instantly assume the 1024 vs 1000 based math for calculating size is the question at hand (it is not). I realize for the Operating system to report 64GB that would mean the drive actually would need to have 64 * 1024 * 1024 * 1024 = 68,719,476,736 bytes so that when you divide by 1024 three times you get back to the number "64" GB. And that is not what the manufacturers do.

In Summary:

Note: Referring to the raw storage capacity of the drive; disregarding MFT, file system overhead, etc... RAW sectors and therefore raw bytes available to the device...

The main questions are:

  1. For a USB Flash drive, would you expect at least 64,000,000,000 bytes (125,000,000 sectors * 512 = 64,000,000,000) to be the size of the drive (as displayed in Windows Disk Management, or Linux Gparted, etc).

  2. Also, does the total amount permanently shrink over time through normal use (drive maintenance)?

mike2000
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  • see if this sheds any light: http://superuser.com/questions/71974/why-is-the-effective-hard-drive-size-lower-than-the-actual-size – fixer1234 Mar 22 '15 at 05:57
  • For memory storage devices (USB, SSD), the chips used for the devices have 2^n storage bits. So a 64 MB USB drive should have 68,719,476,736 bytes of storage. Of course, once you format the drive, there will be considerably less. – LDC3 Mar 22 '15 at 05:58
  • Actually there is 64,000,000,000 (or a "little extra") to actually give you what you pay for (Gigabytes). You are thinking of "Gibibytes". Gigabyte = 10^3 Gibibyte = 2^30 (source: http://en.wikipedia.org/wiki/Gibibyte ) So when your operating system reports what you *think* is 64MB you are actually seeing it reported in GiB (Gibityes) which is 59.6 GiB. I understand the 1024 vs 1000 factor and space taken up by the MFT and File system. I'm asking about **raw** amount of sectors and when multiplying that by 512 I expected to see at least 64,000,000,000 bytes.At least based on HDD – mike2000 Mar 22 '15 at 18:39
  • Correction: Gigabyte = 1000^3 MB – mike2000 Mar 29 '15 at 16:45
  • Also, the USB should only have 64,000,000,000 bytes (not 68 GB). And, yes once you account for Microsoft Windows dividing by 1024^3 to display GiB, then formatting, due to Filesystem requirements, it will display even less available free space than 59.6 GB for a 64 GB drive. My concern is more to do with having **less** than the originally purchased amount of raw 64 GB of storage flash cells. After some more testing it *seems* each company varies, but I'm still not sure I'm seeing what is considered "normal".The variation is extremely wide (loss of 700 MB in one brand, 900 MB in another). – mike2000 Mar 29 '15 at 16:53
  • Correction #2: Sorry to anyone that is confused by my first correction. I'm just going to put my source link here: http://en.wikipedia.org/wiki/Gibibyte. What the correction should have said was "1 Gigabyte = 1000^3 bytes", and "1 Gibibyte = 1024^3 bytes, or 2^30 bytes". – mike2000 Mar 29 '15 at 16:55

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