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Is BitLocker Slowing My File Transfer Speeds?

Brandon Byrnes

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Jan 3, 2017
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#1
I just purchased a SanDisk Ultra Fit USB 3.1 Flash Drive 256GB SDCZ430-256G-G46, the first thing I did was enable BitLocker on it and set it up to encrypt files as they were added to it. I am currently trasfering a 76GB folder from my m.2 SSD to the flash drive using TeraCopy, but the transfer speed is only htting around 20MB/s, this seems VERY slow to me. Is this becuase BitLocker is encrypting the files as it transfers them or is this just a crappy flash drive? FYI I am using a usb 3.0 port.
 

Brandon Byrnes

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Jan 3, 2017
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#3
Yes, that'll create a slowdown.

It's having to decrypt and then transfer the files.
Okay thanks for the info, I thought that might be why, I just wasn't sure if it would slow it down that much, my usual transfer speeds are over 100-150mb/s so 20 was reallllllllly slow.
 

Ebony

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Dec 24, 2018
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#4
Ya bitlocker slowdown transfer speed a little bit but not that slow as you are telling there might be other problem
 

Brandon Byrnes

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Jan 3, 2017
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#5
I turned bitlocker off and I'm still only getting write speeds around 4-5 mbps, is there a program that i can run to check if this flashdrive is fake? I bought it off Amazon.
 

Brandon Byrnes

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Jan 3, 2017
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#7
Thanks I'll give one a try. it's going to have to be on my next day off, becuase it looks like all of these programs erase the data thats on the drive, soI'm going to have to backup the 93GB that I alreadt have on it, and if it takes as long as it does to write to the flashdrive then thats going to take a while.
 

Brandon Byrnes

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Jan 3, 2017
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#8
So I used check flash and the flash drive is legit. I Think its just a matter of it not living up to what Sandisk says is supposed to be the write speeds. I did notice that when I put my files back on the flash drive that it went a little faster. I also noticed that my folders with pictures were taking the longest to transfer, but when I went ahead and zipped those folders which each have around 1000 photos, the zipped folders transfered VERY fast compared to the unzipped folders. I did however disable bitlocker on the drive, and that also sped up the transfer speed.
It's strange though, I purchased a 1TB external HDD almost two years ago and enabled bitlocker on that and to this day I get the fastest transfer sppeds with that drive compared to all of the assorted USB 3.0 flashdrives that I own. I would have assumed that it would be slower then the flashdrives becuase it is a mechanical drive, but I guess not.
 

gus

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#9
Sooooo many variables involved comparing external flash drives and HDD's and as you have found already transferring large files usually takes less time than lots of smaller files. Your external controllers, and hardware/drivers also contribute. The advertised transfer speeds are what was achieved under perfect testing conditions also, and you should note the manufacturers often say "up to" a quoted speed??