[GRLUG] Interesting problem with 2.5" backup drive

[John-Thomas Richards]

On Tue, Apr 27, 2010 at 11:37:12PM -0400, Bob Kline wrote:
> On Tue, Apr 27, 2010 at 9:42 PM, John-Thomas Richards
> <jtr at jrichards.org>wrote:
> 
> > On Tue, Apr 27, 2010 at 04:05:46PM -0500, L. V. Lammert wrote:
> > > At 03:17 PM 4/27/2010, you wrote:
> > > >Is it in a USB enclosure?
> > >
> > > Just found the problem - looks like the USB port on ONE machine is
> > > underpowered - tried the disk on a 3rd Linux machine (netbook) and
> > > it mounted with no problem!
> >
> > That makes sense.  My USB cable for my external drive has an extra
> > plug in case one does not provide enough power.  Cool.  Glad you
> > figured it out.
> >
> 
> I have a USB CD-DVD unit like that - two plugs.  Oddly, it specifies
> not using a powered USB hub, which makes more sense to me.  I have an
> HP printer plugged in to a powered hub, and it works just fine.  In
> this case it's not for the power - it has its own power supply.

I'm surprised a CD-DVD unit wouldn't require more power than a hard
drive.  I'm not sure why a powered hub is not recommended.

> So I'm not totally clear about what goes on here.  Maybe the second
> plug only taps power, and not signal? But even then, a powered hub
> would seem to work with a single ended cable....

The second plug is for power only.  My harddrive works fine with one
plug connected.  If I use the extra plug only, it'll power up but won't
mount (since it's not sending a signal).
-- 
john-thomas
------
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themselves down before; they always did, they always will; and if you don't
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Oliver Wendell Holmes, Sr., poet, novelist, and physician (1809-1894)