Re: USB 2.0 with 250Gb disk and insane loads

From: Oliver Neukum (
Date: Sun Jun 01 2003 - 09:53:47 EST

Am Sonntag, 1. Juni 2003 16:31 schrieb David Brownell:
> > I'm trying to nail own a problem here, with my shiny new Maxtor 250Gb
> > USB 2.0 disk. Under 2.4 (vanilla, latest 21-preX and 21-preX-acY) the
> > disk will mount and talk nicely. As soon as any load hits it, e.g. a
> > single cp from my internal CD-ROM to the disk, the mahcine load will
> > sky-rocket and at some point within a few minuter hang the machine.
> >
> > On 2.5 (vanilla and -mm) the load will show as i/o-wait and at some
> > point hang any access to the drive, but the kernel will go on working.
> That's a big clue -- nothing in the USB code ever shows up
> as "i/o wait". It can't, since USB is usually built as
> modules and things like io_schedule() are, for some odd
> reason, never exported for use in modules. So USB I/O
> can't use them, and won't show up as "i/o" ... and that
> load must come from some place other than USB.

Probably the block layer as it waits for free io slots.
But that doesn't tell us why the requests are not executed.
Where is SCSI timeout kicking in?
Have you tried enabling debugging in storage?
Could you try on USB1.1 only?


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