Hans Petter Selasky wrote:
> On Saturday 21 August 2010 17:37:18 indulekha wrote:
> > On Sat, 2010-08-21 at 17:18 +0200, Hans Petter Selasky wrote:
> > > > Yes, there is a dmesg error:
> > > > 
> > > > ugen4.5: <(null)> at usbus4 (disconnected)
> > > > uhub_reattach_port:435: could not allocate new device!
> > > > 
> > > > But then just a few lines later, dmesg says:
> > > > 
> > > > ugen4.5: <Seagate> at usbus4
> > > > umass1: <Seagate Portable, class 0/0, rev 2.00/1.30, addr 5> on usbus4
> > > > umass1:  SCSI over Bulk-Only; quirks = 0x0000
> > > > umass1:3:1:-1: Attached to scbus3
> > > > da1 at umass-sim1 bus 1 target 0 lun 0
> > > > da1: <Seagate Portable 0130> Fixed Direct Access SCSI-4 device
> > > > da1: 40.000MB/s transfers
> > > > da1: 305245MB (625142448 512 byte sectors: 255H 63S/T 38913C)
> > > > 
> > > > I'm thinking there's some sort of power management scheme in the
> > > > Seagate that umass has trouble accommodating.
> > > 
> > > Does your USB device have a separate power supply?
> > > 
> > > --HPS


Joining late, sorry

> > No, it's one of those pocket-sized HDDs.
> > This one, actually:
> > http://www.amazon.com/gp/product/B001SJZV10/ref=oss_product

No current rating at 
 
http://www.seagate.com/ww/v/index.jsp?name=ST903204EXM101-RK-apac-expansion-portable-usb-320gb-hd&vgnextoid=16816583b2561210VgnVCM1000001a48090aRCRD&locale=en-US#TabContentSpecifications

> Hi,
> 
> Try to use an external self-powered USB HUB and see if the problem is the 
> same.

Yes,
PS Ive had so much grief with USB over the years, I cut out some
USB sockets off a dead mboard, so I can intercept & meausure voltage
& current on USB devices.

USB 1 & 2 is spec'd at <= 0.5 Amp, (more on USB3 later)

As well as the hub,
A power doubler USB Y leads into 2 sockets of the hub may help,
also plug both of those in before the disc in the other end.  (else
voltage droop while disc spins may confuse disc internal logic).

PPS HPS Re that suspicion above, I also have a device that used to
confuse usbd & prob. still confuses devd, (I guess it was turning
itself off after listening to cable, anyway it's free if you or
another USB developer wants to play with it, contact me.
http://berklix.com/~jhs/txt/clipman/

Cheers,
Julian
-- 
Julian Stacey: BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com
 Mail plain text,  Not HTML, quoted-printable & base 64 dumped with spam.
        Avoid top posting, It cripples itemised cumulative responses.
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