Bytecc 2.5" External Drive Enclosure - bus power supplies enough juice?

[Daniel Armstrong]

On 3/8/06, Madison Kelly <linux-5ZoueyuiTZhBDgjK7y7TUQ at public.gmane.org> wrote:
> Daniel Armstrong wrote:
> > Are these external drive enclosures that draw power from the USB ports
> > getting enough juice to run properly?
> >
> > I am interested in combining a 60GB laptop drive with the Bytecc
> > HD1-U2 2.5" USB2.0 Aluminum HDD Enclosure:
> >
> IIRC, Bytecc use a horrible chip which often locks up hard when you
> start a transfer of any decent size. I can't think of the chipset off
> the top of my head though, sorry. My personal opinion is to stay *far*
> away from Bytecc... they're cheap for a reason.
>
> On the other hand, I have had good luck with Vantec's line, though I
> have only used their 3.5" carriers. Generally speaking though; any
> carrier that draws power from the USB bus will need ~500mA which is more
> than the spec allows (350mA/channel). To get around this they generally
> give you a USB pass-through cable that provides extra power for the
> drive. These pass-throughs should only be put in between low-power or
> self-powered USB devices (ie: a mouse).
>
> The real test is to look at the power draw on the hard drive you want to
> use and add ~20/30mA for the controller. Then see if one or two ports
> will provide enough power for you.

Thanks for the feedback Madison.

Considering your tip about Vantec, I checked out the Vantec NexStar3
NST-260U2, a 2.5" external drive enclosure that connects to 2 USB
ports for power.

The laptop drive I want to make use of is a 60GB Hitachi DK23FB-60. I
found a pdf of the drive specifications online. It states that during
seek/read/write operations it requires power in a range of 400-450mA,
but I see that at initial startup the drive draws 900mA of power.

I am not familiar with electrical terms, but looking around online -
if I understand correctly - it appears a USB device can draw 500mA
from each USB port. Connecting to 2 USB ports should supply 1000mA and
be enough power to spin up this drive and the controller?
--
The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml