Re: aic7xxx sets CDR offline, how to reset?

Andries Brouwer
2002-09-04T10:37:37Z

On Tue, Sep 03, 2002 at 04:48:39PM -0500, James Bottomley wrote:

> If you're hitting error recovery so often that whether it recovers
> in half a second or several seconds makes a difference, I'd say
> there's something else wrong.

Not that I want to contradict, but an example.
Without my sd.c patch from yesterday or so (fixing MODE SENSE calls)
an "insmod usb-storage.o" would take 14 minutes and 6 seconds for me.

[One USB device, with 3 subdevices, gets into a bad state when
presented with a MODE SENSE command that asks for more than the
56 bytes it has available. For each of the three subdevices we
get a long sequence of retries, abort, reset, host reset, bus reset
before it is taken off-line.]

The scsi error recovery has many bad properties, but one is its slowness.
Once it gets triggered on a machine with SCSI disks it is common to
have a dead system for several minutes. I have not yet met a situation
in which rebooting was not preferable above scsi error recovery,
especially since the attempt to recover often fails.

Andries