How Fast is USB 2.0?

[ME]

I have an external USB 2.0 enclosure hooking directly to USB port on my Dell
PC. The speed when I transfer files b/w the external drive and the PC is
not as I expected. It takes more than 30 minutes to transfer 4GB of data.
Is this accepted for a USB connection? The external drive is WD 250GB. PC
is XP SP2 with USB 2.0 driver loaded . Thanks.

 

[Mike Coppins]

I have an external USB 2.0 enclosure hooking directly to USB port on my Dell
PC. The speed when I transfer files b/w the external drive and the PC is
not as I expected. It takes more than 30 minutes to transfer 4GB of data.
Is this accepted for a USB connection? The external drive is WD 250GB. PC
is XP SP2 with USB 2.0 driver loaded . Thanks.

"an external USB 2.0 enclosure"? Do you mean a hub? Does it connect to
a USB 2.0 port on your computer? I'd take the hub out if you want
slightly better performance. Are there many other USB devices connected?

Also, what sort of data is the 4GB? Lots of little files? How fast is
the hard disk being copied from?

USB 2.0's spec says 480MBits/sec. Divide that by 8 for megabytes/sec =
60. That's the theoretical maximum speed. However, it'll be a long
while yet (in terms of technology) before you can expect 60MB/sec for
copying lots of tiny files, the speed will go down to probably about
15MB/sec given a decent hard disk being copied from and to. Given that
you're copying to USB, I'd reduce that to 10MB/sec.

My maths was never my strong point, but assuming it took your PC 45
minutes to do the copy, that's 1.5MB/sec, which is too high for USB 1.1,
and rather low for USB 2.0. Something is performing poorly or is
sapping system resources.

Is your main hard disk doing DMA? You can check that in IDE devices in
the device manager.

 

[ME]

what I meant is the USB case for external drive. Here is one:
http://www.atacom.com/program/ataco...USER_ID=www&PAGE_LIST=USB_FIRE_enclosure_copy.
I put a WD 250GB hd and XP recognized the drive with no problem. This is a
direct connection, no hub in between. You may be right with the DMA setup.
My Dell supports DMA but last time I had to modify registry to change a DVD
burner to DMA. Changing in Device Manager didn't take effect.

 

[zibby]

Switch to FireWire 800. I'm pushing 60Mb/s
USB enclosures are always slow. some perform better than others. It all
depends on controller chips used. I tested few and most I got was 15Mb/s

 

[Alex Nichol]

I have an external USB 2.0 enclosure hooking directly to USB port on my Dell
PC. The speed when I transfer files b/w the external drive and the PC is
not as I expected. It takes more than 30 minutes to transfer 4GB of data.
Is this accepted for a USB connection? The external drive is WD 250GB. PC
is XP SP2 with USB 2.0 driver loaded . Thanks.

The controller on the machine into which you plug the USB2.0 device must
itself be USB 2.0 hardware. Where there are multiple ports and the
machine has nominal USB 2.0 support, not all ports may have it

 

[ME]

how do I tell the controller is usb 2.0 hardware? Dell sold the PC said it
is usb 2.0. I have a powered external 1.1 hub hooked up to the Dell. When
I plugged the usb cord of an HP printer to the hub the screen popped up a
message saying I should plug into a 2.0 port.

 

[Admiral Q]

Open Device Manager, scroll down to "Universal Serial Bus controllers" and
click on the "+" sign, it you have an USB 2.0 controller, it will say
something like "USB 2.0 Enhanced Controller" or "USB Enhanced Controller" -
the key word being "enhanced".

--
Star Fleet Admiral Q @ your service!

how do I tell the controller is usb 2.0 hardware? Dell sold the PC said it
is usb 2.0. I have a powered external 1.1 hub hooked up to the Dell. When
I plugged the usb cord of an HP printer to the hub the screen popped up a
message saying I should plug into a 2.0 port.

 

[yabbadoo]

USB 1.1 plugged into USB 2 port will operate as 1.1 (backward compatability
of USB2)

USB 2 printer needs to be direct into USB2 port, not the 1.1 hub - which is
what in effect it's telling you - but nevertheless printer should still
work, at 1.1 speed.

HTH Len

how do I tell the controller is usb 2.0 hardware? Dell sold the PC said
it is usb 2.0. I have a powered external 1.1 hub hooked up to the Dell.
When I plugged the usb cord of an HP printer to the hub the screen popped
up a message saying I should plug into a 2.0 port.

 

[ME]

yes I do have the Intel USB 2.0 Enhanced Host Controller. It still won't
explain the extremely transfer speed.

Open Device Manager, scroll down to "Universal Serial Bus controllers" and
click on the "+" sign, it you have an USB 2.0 controller, it will say
something like "USB 2.0 Enhanced Controller" or "USB Enhanced
Controller" -
the key word being "enhanced".

 

[ME]

I know the bottle neck at the hub.

USB 1.1 plugged into USB 2 port will operate as 1.1 (backward
compatability of USB2)

USB 2 printer needs to be direct into USB2 port, not the 1.1 hub - which
is what in effect it's telling you - but nevertheless printer should still
work, at 1.1 speed.

HTH Len

 

[yabbadoo]

It's not a hub bottleneck. It's because it's a USB1.1 hub. You can't get
USB2 speed from a device connected to a 1.1 hub. You need to use a USB2 hub,
else the USB2 port defaults to 1.1 for any/all devices connected to the 1.1
hub.

Since it's a printer, best practice anyway to connect direct to USB2 port
rather than through a hub - a permanent connection if possible. This
maximises speed, ensures staability of settings, avoids hub bottleneck.
Sincerely, Len

 

[ME]

what i meant the bottle neck was the traffic is down to 1.1 at the hub,
regardless the number of devices hooked up to the hub. whatever, in my case
i do have the printer connected directly to the usb port on the back.

 

[yabbadoo]

Your post 20 Jan timed 21.30 - (the point I and others addressed)

QUOTE..... When I plugged the usb cord of an HP printer to the hub the
screen popped up a message saying I should plug into a 2.0 port. UNQUOTE

To answer the question about (relative) speed of data transfer with USB

Speed - HDD transfer to external device is slower than the reverse path
(write time of HDD is optimum fast)
Direct port versus hub port - direct port is faster than using hub port,
it's a shorter electronic path.
Type of data file being transferred affects speed of transfer, as does
degree of fragmentation of large files.

In all cases, USB2 is noticeably faster than USB1. The degree is dependant
on any/all the 3 conditions above, so is a variable, not a constant.

Sincerely, Len.