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Why was it uselessly slow from a USB 3 flash drive? - Printable Version

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Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 04-11-2016

I've tried using WinToUSB on both a 32 GB USB 3 flash drive and a really old 160 GB  mechanical (spinning) drive.


I've tested both, and the flash drive has much faster read/write speeds than the spinning drive. It can do like 130/60 MBps, while the spinning drive is more like 27/27.

Yet, when I tried to install Windows 10 on the flash drive, and booted from it, it was painfully slow. It froze all the time, and was basically useless.

Running from the (8 year old) mechanical drive, it works just fine! It's probably not at optimal speed, but it's just fine for my needs.

I remember getting a warning while installing to the flash drive, saying that it might not work very well on that drive. But why is that? Isn't read/write speed the most important thing? What limitations are there on the USB 3 flash drive that made running Windows from it not work? I mean, it's read/write speeds are so fast!

RE: Why was it uselessly slow from a USB 3 flash drive? - admin - 04-11-2016

For an Windows operating system boot drive, 4K random read speeds are the most important, followed by 4K random write speed, this is because there are a large number of small files in the Windows system. The 4K read/write speeds of the common flash drives are always slow, so these drives are not suitable for creating W2G drive.
And the read/write speeds you said is sequential write read/write speed, not 4K random read/write speed, so it can't run Windows smoothly.

RE: Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 04-12-2016

(04-11-2016, 10:37 PM)admin Wrote: For an Windows operating system boot drive, 4K random read speeds are the most important, followed by 4K random write speed, this is because there are a large number of small files in the Windows system.  The 4K read/write speeds of the common flash drives are always slow, so these drives are not suitable for creating W2G drive.
And the read/write speeds you said is sequential write read/write speed, not 4K random read/write speed, so it can't run Windows smoothly.

I see. I don't know what 4K read/write speed is, but anyway, I don't really need to know. Thanks for the answer.

This may be somewhat off topic, but is this only the case for Windows OS? Because when I run Linux off the same flash drive, there is no problem?

RE: Why was it uselessly slow from a USB 3 flash drive? - admin - 04-13-2016

There is no denying that Linux does it better than Windows. For more information about sequential read/write and 4K random read/write, please visit:
http://www.buildcomputers.net/hard-drive-benchmark.html

RE: Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 04-13-2016

Thanks Smile

RE: Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 04-16-2016

I did a benchmark of both my USB 3 flash drive, and the old, mechanical, spinning drive. It looks like the USB 3 flash drive performs much better, even when it comes to 4k read write. So why is it so hopeless to run Windows from it, then?

Here is the old USB spinning drive ( the one I'm currently running Windows from.)

Microsoft Virtual Disk 136GB
(9 User benchmarks - Rank 170 - Average bench 58%)
96GB free
Firmware: 1.0
SYSTEM 4KALIGNED
Performing way below expectations (5th percentile)
Rank 931
16.7%
Read 30.9
Write 26.9
Mixed 9.81
16% 22.5 MB/s
4K Read 0.31
4K Write 1.39
4K Mixed 0.22
64% 0.64 MB/s


Here is the USB 3 flash drive that Windows ran terribly slow from:


SanDisk Ultra USB 3.0 32GB-$9
(962 User benchmarks - Rank 121 - Average bench 26%)
24GB free, PID 5581
Operating at USB 3.0 Speed
Performing way above expectations (98th percentile)
Rank 29
40.6%
Read 140
Write 59.7
Mixed 26.5
77% 75.3 MB/s
4K Read 4.39
4K Write 2.03
4K Mixed 1.24
127% 2.55 MB/s


Here are the full results: http://www.userbenchmark.com/UserRun/1002256

So why did the USB 3 flash drive perform better in every way on the test? Yet, Windows runs just fine from the spinning USB drive, but terribly from the flash drive? Why is this?

RE: Why was it uselessly slow from a USB 3 flash drive? - jksynapse - 09-10-2016

I totally agree, it happens same with Me

did you install in SSD with VHD mode?
I will try to install in SSD with Legacy mode not VHD, and will see if it will work better, and let you know also

RE: Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 09-10-2016

(09-10-2016, 04:45 AM)jksynapse Wrote: I totally agree, it happens same with Me

did you install in SSD with VHD mode?
I will try to install in SSD with Legacy mode not VHD,  and will see if it will work better, and let you know also

It wasn't a SSD. As you can see from the above post, it was a flash drive, this one:
[Image: sandisk-32gb-ultra-usb-3-0-flash-drive-s...0-full.jpg]

I don't think VHD versus legacy matters much. It's a hardware thing.

RE: Why was it uselessly slow from a USB 3 flash drive? - darksurf - 11-09-2017

https://youtu.be/4Sae9wL_008

Is this the problem? The drive is not set in performance mode and write caching is disabled?

RE: Why was it uselessly slow from a USB 3 flash drive? - Fiksdal - 11-09-2017

(11-09-2017, 11:37 AM)darksurf Wrote: https://youtu.be/4Sae9wL_008

Is this the problem? The drive is not set in performance mode and write caching is disabled?


No.