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-   -   can USB ports have on/off switches? (http://www.linuxquestions.org/questions/general-10/can-usb-ports-have-on-off-switches-4175475648/)

newbiesforever 09-02-2013 11:44 PM

can USB ports have on/off switches?
 
I read some customer reviews of aftermarket USB hubs and saw one say, in listing pros and cons, that the ports on the hub in question had no on/off switches. Can USB ports be switched off, or did the reviewer not know what he/she was talking about? I've never used USB hubs other than what my case and motherboard provide, and none of their ports have had off switches. It might be useful in some situations--if you had a device plugged into a port and didn't want to unplug it (probably a flash drive) but wanted the computer to completely ignore it for the time being.

dugan 09-02-2013 11:56 PM

Quote:

It might be useful in some situations
The "situation, I would imagine, is to stop other people from sticking flash drive into the ports and stealing your data.

But if the on-off switch is on the externally accessible hub, well...

TobiSGD 09-04-2013 03:08 PM

Quote:

Originally Posted by newbiesforever (Post 5020626)
Can USB ports be switched off, or did the reviewer not know what he/she was talking about?

Yes, they can. All you need to do is to switch of the +5V lane to power of a device. Hubs with switches are available, like this one: https://www.thinkgeek.com/product/e2d2/.

cascade9 09-05-2013 01:32 AM

LOL, that thinkgeek hub has the most stupid blurb I've seen in a long time.

Quote:

But if you're anything like us, you have your hub tucked back somewhere out of the way. And by out of the way, we mean, inconvenient to get to regularly for plugging and unplugging.

This hub is the perfect solution. It has seven ports and seven power switches, enabling you to turn your USB gadgets on and off without unplugging them.
https://www.thinkgeek.com/product/e2d2/

If its hard to get to your hub to unplug devices, its going to be just as hard to get access so you can turn off a switch.......

newbiesforever 09-06-2013 03:16 PM

Quote:

Originally Posted by TobiSGD (Post 5021771)
Yes, they can. All you need to do is to switch of the +5V lane to power of a device. Hubs with switches are available, like this one: https://www.thinkgeek.com/product/e2d2/.

Nice. Before I knew hubs could have switches, I wanted one in the form of a cable; but I'd consider this one.

And how would a Linux operating system respond if a USB storage medium were switched off and then on later? If you switched it off, would it disappear from the system as though no device was plugged into the port? If so, and if it reappeared after being switched back on, would it have the same location (I mean /dev/sda1) as before?

TobiSGD 09-07-2013 07:08 PM

Switching the device off will have the same effect as unplugging the device. If a storage device appears in the same place is not predictable, sometimes even unplugging and plugging in again in a short amount of time will cause a device to appear in a different place.

YellowApple 09-12-2013 06:56 PM

Quote:

Originally Posted by cascade9 (Post 5022049)
LOL, that thinkgeek hub has the most stupid blurb I've seen in a long time.



https://www.thinkgeek.com/product/e2d2/

If its hard to get to your hub to unplug devices, its going to be just as hard to get access so you can turn off a switch.......

Well, it depends on the location; it's possible to be able to barely reach a button while not being able to reach the plugged-in device (or being able to reach said device, but not easily enough for you to grip the device and unplug it).

That said, a USB hub that could have ports switched on/off remotely (maybe using a separate USB device integrated in the hub?) would be cool.

jefro 09-12-2013 08:00 PM

I think they mean powered usb hubs. That would be where some external ac adapter is attached to the hub.


I suggest that you put all of your computer stuff on a switched power supply. That way all the wall warts and vampire losses are stopped.


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