Re: USB Disk Stalls on -current

On Sun, Feb 6, 2022 at 11:32 PM grarpamp <grarpamp@gmail.com> wrote:

> > Feb  6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): READ(10). CDB: 28
> > 00 36 69 02 6e 00 00 80 00
> > Feb  6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): CAM status: CCB
> > request completed with an error
> > Feb  6 11:56:43 alice kernel: (da0:umass-sim1:1:0:0): Retrying command,
> > 2 more tries remain
>
> Isn't there mechanism for kernel/cam/driver to issue a
> sense request to fetch and print the actual error...
>

We do that, but since this is a timeout, there's no sense to
print (otherwise we'd print the sense here). We definitely report
those errors for things like media error, etc.

>
> assuming, which is fine, that the bus or devices aren't
> already locked up, in reset, etc such that a sense
> would go unfulfilled or already be cleared.
>

I'm pretty sure the problem here is that the disks are timing out
for some reason. Many USB drives are designed for occasional
use, and often have aggressive power saving modes, which are
known to hiccup like this. And many USB bridge to SATA chips
have been known to glitch out under load (sometimes transparently
sometimes not).

Warner