Flash drive Slow Down

M

MelonSplitter

[H]ard|Gawd
Joined
Aug 6, 2006
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Why does my new SanDisk Ultra 3.0 starts transferring at about 60mbps then after 10 seconds and 1/4 of the way it slows to 25 mbps?
 
Write cache fills up either on the os allocation side or what is available directly on the flash drive. The transfer then becomes limitted to how fast the solid state storage chips are able to be written to.

If the flash drive has been filled substantially in the past, and the sectors being written to had previously had data which was deleted (ie used sectors are marked as available for writing to again), the chipset that manages reading/writing to the storage chips may have to first trim (clear/zero out) the sector before writing the new data.
 
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MelonSplitter said:
So to remedy this I should format the flash drive before each time I use it?
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Since active trim is not supported on usb flash yes. You need to erase the whole thing - because to get your speed back you need to write to a sector that has no data in it already.
 
it most likely only has a small high speed cache (probberly around 512mb) i assume it does 60MB at the start of transfer
 
Mega6 said:
Just star with a clean partition and test.
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Formatted to NTFS and problem is the same. Starts off at about 60mbps and after about 1/4 of the way it slows down to 24 until complete. Very annoying. Clean install of Win 10 Pro with all updates
 
It's the cache. You just need a faster drive. They sell fast ones, then also get the biggest one for better consistent performance. Or make your own with a msata and little external enclosure, this is a very excellent way.
 
I have the 1st gen sandisk extremes and I think you'll be very happy with it.
 
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