On Wed, 7 Jun 2006, Elladan wrote:
> On Wed, Jun 07, 2006 at 06:15:48PM -0400, Alan Stern wrote:
> > On Wed, 7 Jun 2006, Elladan wrote:
> > > It seems like
> > > the problem is just that Linux gives up on the device much too early.
> > > Alternatively, is there some way to ask Linux to scan this device again?
> >
> > "rmmod usb-storage" followed by "modprobe usb-storage".
>
> The problem with this is that I have other usb-storage devices. I'd
> need a way to just re-probe the one that failed.
There are a couple of ways to do it. For example, you can selectively
unbind and rebind usb-storage to a particular USB interface by writing the
interface's name to the "unbind" and "bind" files in
/sys/bus/usb/drivers/usb-storage.
> > > Here's the device powering on while plugged in:
> > >
> > > usb 3-1.3: new high speed USB device using ehci_hcd and address 9
> > > scsi2 : SCSI emulation for USB Mass Storage devices
> > > usb-storage: device found at 9
> > > usb-storage: waiting for device to settle before scanning
> > > usb 3-1.3: reset high speed USB device using ehci_hcd and address 9
> > > scsi: Device offlined - not ready after error recovery: host 2 channel 0
> > > id 0 lun 0
> > > usb-storage: device scan complete
> >
> > Sounds like the USB interface in the enclosure isn't working very well.
>
> What's the business with "waiting for the device to settle before
> scanning" ? I read this as meaning that it just had some timeout in
> there to deal with these devices taking a while to start up.
It's not a timeout; it's just a delay. Yes, the delay is there because
some devices take a while to start up. You can change the length of that
delay by setting a module parameter for usb-storage. For example, in
/etc/modprobe.conf you might say:
options usb-storage delay_use=10
to make that delay be 10 seconds long instead of the default 5 seconds.
> > > SCSI device sdc: 4294967296 512-byte hdwr sectors (2199023 MB)
> > > sdc: assuming drive cache: write through
> > > SCSI device sdc: 4294967295 512-byte hdwr sectors (2199023 MB)
> > > sdc: assuming drive cache: write through
> > > sdc: sdc1
> > > Attached scsi disk sdc at scsi3, channel 0, id 0, lun 0
> > > Attached scsi generic sg2 at scsi3, channel 0, id 0, lun 0, type 0
> > > usb-storage: device scan complete
> >
> > You don't think this rather sad IDE disk actually has a 2199 GB capacity?
> > More likely the enclosure is sending back bogus data.
>
> It returned -1 sectors... A bit odd, but clearly a magic number and not
> garbage.
On the contrary -- clearly garbage and not a magic number. A value of -1
means the device returned data in which all the bits are turned on,
typical of what happens when a semiconductor device fails. It does not
have any special magic meaning.
Alan Stern
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