dongism
Posts: 3
Joined: Thu Jun 25, 2015 11:35 pm

Cheapest powered hub for just an external hard drive?

Thu Jun 25, 2015 11:45 pm

Title pretty much says it all.

I bought my Raspberry Pi a couple days ago and all the stuff I needed (or so I thought) arrived today. I was having some issues with the external USB hard drive not working for some reason. Some googling later, I find out that I need a powered USB hub.

So, what's the cheapest one available from Amazon (an item with Prime shipping)? I don't care if it's USB 2.0 or 3.0. My RPi is already being powered with a dedicated wall outlet.

W. H. Heydt
Posts: 10326
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 12:39 am

Since you have independent power for your Pi, make sure you get a hub that *doesn't* feed power back through the USB port it's connected to. You really don't want "dueling power supplies". Unfortunately, cheap hubs tend to try to back power.

The hub I use (when I need a powered hub for a Pi) is this one: http://www.mcmelectronics.com/product/83-12399

That said...are you sure you need a hub? If you're using a Model B+ or Pi2B you can make up to 1.2A available to the USB ports.

dongism
Posts: 3
Joined: Thu Jun 25, 2015 11:35 pm

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 12:42 am

W. H. Heydt wrote:Since you have independent power for your Pi, make sure you get a hub that *doesn't* feed power back through the USB port it's connected to. You really don't want "dueling power supplies". Unfortunately, cheap hubs tend to try to back power.

The hub I use (when I need a powered hub for a Pi) is this one: http://www.mcmelectronics.com/product/83-12399

That said...are you sure you need a hub? If you're using a Model B+ or Pi2B you can make up to 1.2A available to the USB ports.
I would honestly prefer to not buy a hub (or really anything else). Yes, I do have the Pi2B. However, it appears to not be getting enough power to the hard drive to actually start up the hard drive. Is there a certain thing I have to do?

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mikronauts
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Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 1:23 am

If your drive is a 2.5" drive:

Edit /boot/config.txt

add the following line:

max_usb_current = 1

save and reboot
dongism wrote:
W. H. Heydt wrote:Since you have independent power for your Pi, make sure you get a hub that *doesn't* feed power back through the USB port it's connected to. You really don't want "dueling power supplies". Unfortunately, cheap hubs tend to try to back power.

The hub I use (when I need a powered hub for a Pi) is this one: http://www.mcmelectronics.com/product/83-12399

That said...are you sure you need a hub? If you're using a Model B+ or Pi2B you can make up to 1.2A available to the USB ports.
I would honestly prefer to not buy a hub (or really anything else). Yes, I do have the Pi2B. However, it appears to not be getting enough power to the hard drive to actually start up the hard drive. Is there a certain thing I have to do?
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

dongism
Posts: 3
Joined: Thu Jun 25, 2015 11:35 pm

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 2:14 am

mikronauts wrote:If your drive is a 2.5" drive:

Edit /boot/config.txt

add the following line:

max_usb_current = 1

save and reboot
dongism wrote:
W. H. Heydt wrote:Since you have independent power for your Pi, make sure you get a hub that *doesn't* feed power back through the USB port it's connected to. You really don't want "dueling power supplies". Unfortunately, cheap hubs tend to try to back power.

The hub I use (when I need a powered hub for a Pi) is this one: http://www.mcmelectronics.com/product/83-12399

That said...are you sure you need a hub? If you're using a Model B+ or Pi2B you can make up to 1.2A available to the USB ports.
I would honestly prefer to not buy a hub (or really anything else). Yes, I do have the Pi2B. However, it appears to not be getting enough power to the hard drive to actually start up the hard drive. Is there a certain thing I have to do?
Thanks, that worked!

Joe Schmoe
Posts: 4277
Joined: Sun Jan 15, 2012 1:11 pm

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 2:56 am

I often wonder why max_usb_current isn't the default.

Is there any reason *not* to have it enabled?
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

W. H. Heydt
Posts: 10326
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 4:49 am

Joe Schmoe wrote:I often wonder why max_usb_current isn't the default.

Is there any reason *not* to have it enabled?
Glad it worked...and it goes to show why sometimes people answer a question that is a bit different from what is asked. (I kind of read between the lines to provide advice.)

With the lower power setting, the Pi can do most things that are called for. For instance, I have a Pi2B that normally has keyboard, mouse, WiFi dongle and a USB stick connected. The default 600mA is quite sufficient for that. With the lower power setting, one can run the Pi with a less capable, or otherwise marginal, PSU. (Not that I do that...I'm using the Adafruit 5.25v 2A unit) So the low power setting will, to a degree, make it possible for more people to get their Pi up initially than if it immediately leapt to full 1.2A and they tried loading it to that spec.

Joe Schmoe
Posts: 4277
Joined: Sun Jan 15, 2012 1:11 pm

Re: Cheapest powered hub for just an external hard drive?

Fri Jun 26, 2015 8:05 am

That doesn't sound right to me. Remember, current is only used if you use it...
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

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