[SOLVED] USB Question

business_kid · 12-22-2021, 12:19 PM

My box has 2 usb2 ports and 2 usb3 ports. Received wisdom is that usb is faster/better for things like file transfers. Now either my box is situated where the Bermuda Triangle intersects with the Twilight Zone, or there's a hardware fault. I've experimented with a number of goos usb pluggable devices. I'll attach disk timings:

1. A Known Good usb backup 2.5" drive in USB3

Code:

/dev/sdb:
 Timing cached reads:   7722 MB in  2.00 seconds = 3867.23 MB/sec
 Timing buffered disk reads: 120 MB in  3.04 seconds =  39.50 MB/sec

2. The same in USB2 socket

Code:

 /dev/sdb:
 Timing cached reads:   10276 MB in  2.00 seconds = 5149.32 MB/sec
 Timing buffered disk reads: 398 MB in  3.01 seconds = 132.32 MB/sec

I'm doing an rsync of media to get around formatting weirdness and tried running the rsync on a number of 2.1G episodes on the usb2 & usb3 sockets Both returned times of 50 seconds per 2.1G episode, or roughly 40MB/s.

Apart from the fact that rsync was mounted, and the hdparm was not, is it just a lousy usb3 performance here? USB 2 & 3 is part of Intel series 7 chipset - 2012 vintage.

rigor · 12-22-2021, 08:34 PM

business_kid:

Was this portion of your comment:

Quote:

Originally Posted by business_kid

...Received wisdom is that usb is faster/better for things like file transfers...

intended to suggest that USB3 is faster than USB2? If so, you might want to consider the difference in the physical connectors that is used to achieve the higher speed of USB3, and how that might impact your situation: https://en.wikipedia.org/wiki/USB_ha..._compatibility

pan64 · 12-23-2021, 01:42 AM

that is the cache I think. The data was not really written to the usb device. You need to run sync/umount/eject or similar to really complete that operation.

TenTenths · 12-23-2021, 06:02 AM

Quote:

Originally Posted by business_kid

Apart from the fact that rsync was mounted, and the hdparm was not, is it just a lousy usb3 performance here? USB 2 & 3 is part of Intel series 7 chipset - 2012 vintage.

The bottleneck in terms of speed will NOT be the USB2/USB3 implementation. For any storage device it's the device itself that will be the slow part and unless it's really fast you'll see identical performance times on USB2/USB3. If you're transferring "real" files from one device to another then both device speeds come in to play.

For a fast device it can be different, just for fun, and because it beats working, I did the CrystalDiskMark 8 tests with a Dell XPS laptop and a fast Lexar SDXC card. The card is rated as "250MB/s Read" These are the SEQ1M Q8T1 test results

Onboard SD card reader: Read 92.20MB/s, Write 89.08MB/s
Lexar USB3.0 card reader direct to USB-C port: Read 225.86MB/s, 114.49MB/s
Same card reader, USB3 port on cheapo USB-C multi-function hub: Read: 35.23MB/s, 29.50MB/s
Same card reader, USB2 port on cheapo USB-C multi-function hub: Read: 35.44MB/s, 29.35MB/s
Same card reader, USB-C to USB adaptor that came with the lappy: Read: 91.17MB/s, 86.19MB/s

So, for exactly the same device speeds can vary wildly depending on exactly what it's attached to.

business_kid · 12-23-2021, 06:07 AM

Quote:

Originally Posted by rigor

business_kid:

Was this portion of your comment:intended to suggest that USB3 is faster than USB2? If so, you might want to consider the difference in the physical connectors that is used to achieve the higher speed of USB3, and how that might impact your situation: https://en.wikipedia.org/wiki/USB_ha..._compatibility

I have two usb3 drive caddies here, USB with about 250mm leads, and usb3 plugs (the top one from your link). The laptop is a nine year old Samsung NP350 type which is still made today. never got indications on usb socket specs, so I just used what seemed faster as usb3. They certainly have current capacity for charging. I might have to go looking for those extra pins in the usb3 socket. No fun, as I'm disabled.

business_kid · 12-23-2021, 12:00 PM

Quote:

Originally Posted by TenTenths

Lexar USB3.0 card reader direct to USB-C port: Read 225.86MB/s, 114.49MB/s

Usb-C wasn't included in the laptop. I only have USB-A ports. I don't think usb-C was on laptops in 2012, certainly not mine. What upset me was that hdparm was showing roughly 5 times the speed on tests to usb keys (not shown), and 3.5 times the speed to drives (shown in post #1). My card reader is usb-2.0 and unspectacular, but still nearly as fast as the usb-3 ports.

It shows my usb-3.0 is way off the pace, but beyond that we're guessing really.