Quite some time ago I used a friend's computer. I can't remember exactly what I was doing; but as part of whatever it was, I needed to use a USB flash drive. At a point in time soon after connecting the drive to his computer, and while viewing the drive properties through Windows Explorer, I noticed just over thirty megabytes of space became occupied without any user instruction. Within seconds, the drive again showed empty; however, the total amount of space available within that drive was then that same amount of megabytes short. What can be the cause of this strange behavior?
closed as off-topic by RoraΖ, Stephane, TildalWave, Jens Erat, Ayrx Dec 20 '14 at 15:53
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question does not appear to be about Information security within the scope defined in the help center." – RoraΖ, Stephane, Ayrx
This doesn't seem suspicious at all. As raz pointed out, Windows makes rapid estimates of space and then replaces that number with the real number after finishing calculations.
Also, all disks need to reserve space, but again, as raz mentioned, 32Mb is not unreasonable.
Windows was measuring the speed of the drive for ReadyBoost.
You can disable this in the same drive properties.