[plug] 2.5 USB Enclosure

Chris Caston caston at arach.net.au
Sat Aug 6 11:12:24 WST 2005


On Sat, 2005-08-06 at 01:31, Craig Ringer wrote:
> On Fri, 2005-08-05 at 21:32 +0800, Chris Caston wrote:
> 
> > OK I had trouble with 10gb drives but not with 40gb and above.
> 
> It's entirely possible that the issues you encountered were to do with
> power draw. Did you check the power requirements of the drives? IIRC USB
> guarantees 500 milliamps (certainly < 1 amp) at 5V. Some host controller
> implementations provide a *LOT* more than that when required, some stick
> close to the standard. Laptops seem to be stricter about max power draw,
> especially Intel-chipset laptops.
> 
> I've also found that all other things being equal, newer hardware tends
> to be willing to supply more power. In particular, lots of manufacturers
> seem to support much greater draws in USB2 chipsets, even though the
> standard didn't increase the max permitted power draw for USB2 (AFAIK).
> 
> --
> Craig Ringer

I had a customer with a USB hub that would suck most of the power out of
the machine sometimes killing the PSU other times making it unable to
start.


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