Slow write speed/new USB 3.0 Sandisk 16GB thumb drive

yadda

Senior member
Oct 10, 1999
449
0
76
I just received in 2 USB 3.0 Sandisk Flair drives and the max transfer rate I can get is 9MB/s. It starts at 36MS/s which would be great but within about 15 sec it drops to about 9 the entire transfer.

I have an Asus laptop on Win10 that has all 3.0 usb slots. I have tried formatting as FAT32 and NTFS without much difference in speed.

When I use an app like HD_speed I see 126 MB/S speeds then a similar drop down to 46MB/s...

ideas???
 
Last edited:

XavierMace

Diamond Member
Apr 20, 2013
4,307
450
126
What are you copying when you get the 9MB/s? If it's a bunch of small files, that's pretty normal.
 

taisingera

Golden Member
Dec 27, 2005
1,138
35
91
I just bought a Sandisk Ultra Flair but 32GB. Using CrystalDisk I get,
Read Seq 148.10 MB/s
Read 4K 5.980 MB/s
Write Seq 44.250 MB/s
Write 4K 2.947 MB/s

Two reasons that the speed might drop, if there is some kind of cache in the drive, when the cache gets empty the speeds might drop (not sure about this though). Second, would be that this drive gets very hot. As it gets hot, the performance might be dropping. I took the drive out after using it for a few minutes benchmarking, and I couldn't believe how hot it was. It felt like touching a car sitting in the sun for a few hours. Also, the smaller flash drives usually have poorer write speeds compared to larger ones, just like SSDs.
 

yadda

Senior member
Oct 10, 1999
449
0
76
I just bought a Sandisk Ultra Flair but 32GB. Using CrystalDisk I get,
Read Seq 148.10 MB/s
Read 4K 5.980 MB/s
Write Seq 44.250 MB/s
Write 4K 2.947 MB/s

Two reasons that the speed might drop, if there is some kind of cache in the drive, when the cache gets empty the speeds might drop (not sure about this though). Second, would be that this drive gets very hot. As it gets hot, the performance might be dropping. I took the drive out after using it for a few minutes benchmarking, and I couldn't believe how hot it was. It felt like touching a car sitting in the sun for a few hours. Also, the smaller flash drives usually have poorer write speeds compared to larger ones, just like SSDs.

If you don't mind copying a 2GB file to this drive what is your sustained speed??? Shouldn't I expect faster sustained speeds. When I pug in an external USB docking station and plug in a bare drive I get sustained 120MB/sec transfer speeds. I just figured from this USB 3.0 thumb it would be faster than 9MB/sec.

Thanks for any ideas...
 

taisingera

Golden Member
Dec 27, 2005
1,138
35
91
I didn't have a 2GB file, but I did have a Linux Mint ISO that was 1.67GB. From my boot SSD, Adata SP920 (525 Read/220 Write), I moved the file to the flash drive. For the first 65% it wrote at 83MB/s but all of a sudden slowed to 20MB/s for the rest of the file for a total time of 46s. I then transferred it back to the SSD, it took about 6s total, and the speed started at 400MB/s and went down to 190MB/s. To me it looks like there is some caching going on to reach those high speeds.
 

taisingera

Golden Member
Dec 27, 2005
1,138
35
91
I think these drives are faulty or get too hot. On Amazon quite a few people complain about all the capacities, 16GB to 128GB where it starts fast writing and then slows down and they get super hot. I just did another test, with a 1.5GB file, and it starts out at 85MB/s for the first 1GB then it dropped to 12-18 MB/s for the rest. I also did this on a bunch of audio files, and probably after the first 1GB of files, it slowed down. Either after writing 1GB of data, the drive gets too hot, or Sandisk is using TLC flash with some cache, and once the cache fills up, the write speed to the TLC part drops badly.

I copied the same 1.5GB file to a Mushkin Ventura Plus 16GB and it stays at a steady 45MB/s and doesn't get nearly as hot.

If you are keeping the drive, make sure to register it at Sandisk, it has a 5 year warranty.
 

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